Lord Maha Vishnu spoke in indirect manner.
There is no fault in speaking that way since Krishna says in SB 11.21.35
paroksha-vada rishayah paroksham mama ca priyam
"The Vedic sages and mantras deal in indirect terms, since they know
that I prefer this indirect method."
A similar idea is expressed in Bhagavad Gita(7.25)
nāhaṁ prakāśaḥ sarvasya yoga-māyā-samāvṛtaḥ mūḍho ’yaṁ nābhijānāti
loko mām ajam avyayam
I am never manifest to the foolish and unintelligent. For them I am
covered by My internal potency, and therefore they do not know that I
am unborn and infallible.
Similar indirect verses can be found in many places.
Vishnu Purana (5.1.59) says
ujjaharatmanah kesau sita-krishnau mahamune: O great sage, he pulled
out black and white hairs from himself.
Mahabharata 1.199.? also says:
sa capi kesau harir udbabarha suklam ekam aparam capi krishnam | tau
capi kesavavisetam yadunam kule striyau rohinim devakim ca ||
tayor eko balabhadro babhuva yo ’sau svetas tasya devasya kesah |
krishno dvitiyah kesavah sambabhuva keso yo ’sau varnatah krishna
uktah ||
"And Hari took up two hairs from his body, one of which hairs was
black and the other white. And those two hairs entered the wombs of
two of the Yadu race, by name Devaki and Rohini. And one of these
hairs viz., that which was white, became Baladeva. And the hair that
was black was born as Kesava's self, Krishna."
Mahabharata AnuGita
परं हि बरह्म कथितं यॊगयुक्तेन तन मया
param hi brahma kathitaM
yogayuktena tanmayA
I discoursed to thee on Supreme Brahma, having
concentrated myself in Yoga.
If one examines the superficial meanings of these statements, they are contradictory and therefore should be rejected. Though Näräyana has a body of bliss and knowledge, totally unaffected by the three gunas, he is described as having white and black hair. However he is described as being eternally young in statements such as santaà vayasi kaisore: he has a young age. (SB 3.28.17) And Krishna is stated to be the original form of Bhagavän with the statement krsnas tu bhagavän svayam(SB 1.3.28) whereas here it says he arose from Vishnu’s hair. Therefore the wise will explain these verses differently.
We have following rule from Purva Mimamsa:
śruti-liṅga-vākya-prakaraṇa-sthāna-samākhyānāṁ samavāye
pāra-daurbalyam artha-viprakarṣāt
When direct statement (śruti),
inferential mark or word meaning (liṅga), sentence or syntactical
connection (vākya), context or interdependence (prakaraṇa), position
or order of words (sthāna), and name (samākhyā) are present
simultaneously, each member is progressively weaker in interpretive
force, because of increasing remoteness from the meaning.
(Jaimini-sūtra 3.3.14)
Now, the main verse under the discussion in this question is:
SB 10.89.58:
dvijatmaja me yuvayor didrksuna mayopanita bhuvi dharma-guptaye
kalavatirnav avaner bharasuran hatveha bhuyas tvarayetam anti me
"I brought the brahmana’s sons here because I wanted to see the two of
you, My expansions, who have descended to the earth to save the
principles of religion. As soon as you finish killing the demons who
burden the earth, quickly come back here to Me."
This statement of krishnas tu bhagavan svayam that Krishna is the original form of the Supreme Personality of Godhead appears to contradict the Bhuma-purusha's assertion: "O Krishna and Arjuna, you are both My plenary expansions". The first statement(krsnastu bhagavan svayam) is a direct statement, and the second in the context of an historical narration. For this reason, according to the description given in the Mimamsa-darshanam, the former statement is more authoritative than the second.
These words of the Bhuma-purusha are not to be taken very seriously
for the following reasons:
- The Bhuma-purusha's statement is contradicted by His activity of stealing > > the brahmana's sons just to get the audience of Shri Krishna
(The Bhuma-purusha said: "I have taken away the brahmana's sons
because I am so eager to see You.")
- The statement of Suta Gosvami in the beginning of Shrimad-Bhagavatam and the > instructions of many other exalted speakers
in the Bhagavatam clearly contradict the statement of the
Bhuma-purusha.
The answer is based on commentaries of Jiva Goswami(taken from Krishna Sandarbha) and Vishnwanath Chakravarty Thakur(taken from Sarartha Darshini, they are paraphrased in purports in SB 10.89)
As stated in Hari Vamsa & the above verse, Maha Vishnu stole the children because of his intense desire to see Krishna.
At this time, Lord Krishna desired to amaze and bewilder His friend Arjuna.
This is nothing new, Krishna's activites bewilder even great sages for eg:
SB 10.84.16 The great sages said: Your power of illusion has totally
bewildered us, the most exalted knowers of the truth and leaders among
the universal creators. Ah, how amazing is the behavior of the Supreme
Lord! He covers Himself with His humanlike activities and pretends to
be subject to superior control.
Maha Vishnu smiled (10.89.57) and spoke in grave voice.
Vishnwanath Chakravarty Thakur comments,
"Visnu smiled, indicating “ According to your intentions, I, your
amsa, will reveal by my words my own superior powers, but actually in
those words I will indicate your superiority in form, qualities and
power, and my own position as amsa. See my cleverness.” By this smile
he also indicated his request that Krsna later reveal to Arjuna the
truth about his position"
Arjuna understood it as:
"I brought the brahmana’s sons here because I wanted to see the two of
you, My expansions, who have descended to the earth to save the
principles of religion. As soon as you finish killing the demons who
burden the earth, quickly come back here to Me."
The true intended meaning is:
In the Bhuma-purusha's first statement we may note the following
definitions of words: "yuvayoh" means "of You two", “didrikshuna maya"
means "by Me, who was desiring to see", "me" means "My", "bhuvi" means
“abode", and "upanitah" means "taken away". In the Bhuma-purusha's
second statement, He addresses Krishna and Arjuna as "kalavatirnau".
In this compound word, the word "kala" means "expansions", and the
phrase "along with" is understood. In this way the word is a
"madhya-pada-lopi-samasa", and it means "O Supreme Lord, who has
descended along with all Your vishnu-tattva expansions". Because the
material world is an expansion of the Supreme Lord's energy, the word
"kala" may also be interpreted to mean "in the material world". In
this interpretation the word "kalavatirnau" means "O Lord who has
descended to this material world". That the material world is as
expansion of Lord Krishna's energy is confirmed in the Purusha-sukta
prayers: "pado 'sya vishva-bhutani" (The material world is one quarter
part of the energy of the Supreme Personality of Godhead). The word
"bhuyah" means “again". The last part of the Bhuma-purusha's statement
is: "Please kill the demons who still remain on the earth, and
liberate them, bringing them quickly back to Me". This means that the
demons who are personally killed by the Personality of Godhead become
liberated and enter the Brahman effulgence emanating from the
transcendental body of the Lord's Bhuma-purusha expansion. In this
verse the word "tvarayetam (please cause to quickly arrive)" is in the
causative and the potential mood. The potential is used here to
indicate a prayer or appeal. The word "anti" is an indeclineable
prefix with a dative sense, and it is used here to mean "for the
purpose of" in much the same way as the infinitive is used. It means
here "for the purpose of killing the demons, and granting liberation
to them (tvarayetam)."
The second meaning thus is:
"I wanted to see both of You, and therefore I have brought the sons of
the brahmana here. Both of You have appeared in the material world to
re-establish religious principles, and you have appeared here with all
your potencies and the incarnations who have expanded from You. Please
kill all the demons, and cause them to quickly return to the spiritual
world"
Similarly, next verses can be explained.
Now,
SB 10.89.62: Having seen the domain of Lord Viṣṇu, Arjuna was
totally amazed. He concluded that whatever extraordinary power a
person exhibits can only be a manifestation of Śrī Kṛṣṇa’s mercy.
Vishwanath Chakravarthy Thakur comments on this verse as follows:
"Supremely astonished:" First, seeing the unlimitedly great opulence,
he was amazed, thinking, "Just see, even though I, the son of PANDu,
am a mere mortal, by KRSNa's mercy I have seen the Supreme Personality
of Godhead who is the root cause of everything." Then, pondering for a
short time more, he thought, "Ah, why has He said that <(I took the
[brAhmaNa's] children) out of desire to see you>? How can He who is
the Supreme Personality of Godhead have a desire to see KRSNa, His own
expansion? Perhaps this may be possible due to some temporary
circumstance, but His having said [diRkSuNA] instead of [didRkSatA,]
where the (desiderative) suffix carries the sense of having a
(permanent) characteristic, produces the idea that His desire to see
is perpetual. Even if I grant hypothetically that He always wants
to see, still why does He not see KRSNa present in DvArakA, since
He (MahAkAla) is omnipresent ([vibhutvAt]), since this universe, being
His own creation, is like an [A`malaka] fruit in His hand, and since
personally entered this universe for the purpose of maintanance after
creating it? Perhaps He could not see KRSNa (in DvArakA) because KRSNa
cannot be seen without KRSNa's desiring it. But why would He
(MahAkAla), despite being the merciful Lord of the [brAhmaNas,] create
pain for a [brAhmaNa] year after year? I have to conclude that He
could not abandon His eagerness to see KRSNa, and for that sake has
acted reprehensibly. Let Him act improperly for that sake, but why
could not He have sent some servant to steal the [brAhmaNa's] sons?
Why did He have to come Himself? I think the stealing of them out of
DvArakA must have been impossible for any else to do. Thus I can
understand that His intention was, "Let me cause so much misery to a
[brAhmaNa] of KRSNa's city that he will be unable to tolerate it. Then
KRSNa will give Me His audience." Therefore in His form of the
Supersoul, (Lord MahAkAla) inspired the garrulous [brAhmaNa] to go and
see KRSNa in person and recite to Him his lamentation after the demise
of each of his infant sons. The logical conclusion from this is that
the Godhood of KRSNa is superior (to Lord MahAkAla's)."
Thinking out all this, (Arjuna) became totally amazed. Then Arjuna
inquired from Lord KRSNa, telling Him, "Now I understand the facts."
Lord KRSNa replied, as related in the
[Hari-vaMsa(Vishnu Parva 114.8)
mad-darsanArthaM te bAlA hRtAs tena mahAtmanA viprAtham eSyate kRSNo
mat-sapIpaM na cAnyathA]
"It was for the purpose of seeing Me that He, the Supreme Soul, stole
the children. He thought, 'Only on behalf of a [brAhmaNa's] will
KRSNa come to see Me, not otherwise.' "
But I did not go there for
the [brAhmaNa's] sake; rather I went for the sake of saving the life
of you, my friend. If I were to go there for a [brAhmaNa's] sake, I
would have gone after the first child was stolen. Since I only went
after the ninth child had been taken, it wasn't his request that made
Me go, but yours.
Thus hearing the full truth from Lord KRSNa's mouth, Arjuna thought
that whatever prowess is possessed by any person, even including the
Lord of the spiritual sky, has been obtained only by the mercy of
KRSNa. In this way we should understand that in this last portion of
the Tenth Canto, from the prayers of the personified [Vedas] through
the end of the narration, is found the description of the
superexcellence of the [A`sraya-tattva] (who is the subject) of the
Tenth Canto, KRSNa.
According to Sri Sridhara SvAmi-caraNa, although this took place
before the BhArata War, it is spoken here as included under the
heading of the description of Lord KRSNa's supremacy.
The idea of Krishna being asraya tattva, final shelter of everything(10th topic of bhagavatam as expressed in SB 2.10.1) is also expressed in Bhagavad Gita(7.7)
mattaḥ parataraṁ nānyat kiñcid asti dhanañ-jaya mayi sarvam idaṁ
protaṁ sūtre maṇi-gaṇā iva
O conqueror of wealth, there is no truth superior to Me. Everything
rests upon Me, as pearls are strung on a thread.
Why Arjuna is present if Vishnu wanted to see only Krishna? That is because, Arjuna made a promise to protect the brahmana's children and unable to do so, he was ready to give up life by entering fire. Thus Krishna took Arjuna along with him.
This explanation is in line with Paribhasa sutra(SB 1.3.28, krsnastu bhagavan svayam) as I discussed here.
A similar idea of rarity of beholding Krishna's form is also expressed in Bhagavad-Gita(11.52)[This is talking about other devas not Krishna's incarnations, but it gives us some idea about the rarity of Krishna's form]
śrī-bhagavān uvāca su-durdarśam idaṁ rūpaṁ dṛṣṭavān asi yan mama devā
apy asya rūpasya nityaṁ darśana-kāṅkṣiṇaḥ
The Supreme Personality of Godhead said: My dear Arjuna, this form of
Mine you are now seeing is very rare to see. Even the demigods
are ever seeking the opportunity to see this form, which is so dear.
Some interpret the word idam to refer to the Universal form whereas some interpret that idam rupam means this two handed form of Krishna which he just displayed to Arjuna as seen from 11.51 thus following the natural flow of the verses.
The latter interpretation that idam refers to Krishna's two handed form seems more reasonable for the following reasons:
The word tu (but) at the beginning of verse 11.54 indicates a
different subject matter. This indicates that this form which is
difficult to see, mentioned in verse 11.52 to 11.54, is not the
thousand-headed form, because the previous description in verse 11.50
and 11.51, specifically concerning the Lord’s human-like four-armed
form, is continuous with this topic, and separate from the topic of
the thousand-headed form. Otherwise there would be the fault of
redundant statement in verse 11.53 of what was stated in verse 11.48
concerning the thousand-headed form, if we were to say that verse
11.53 was also concerning the thousand-headed form.
UPDATE:
I checked Sri Vaishnava commentaries regarding these, these verses are interpreted in indirect manner, not superficially:
Vishnu Purana 5.1.59, kesa is taken as hair by modern translators.
Sri Vaishnava commentator quotes from Moksha dharma where in meaning of the name Keshava is explained to give different meaning of kesa.
And regarding verses about Krishna and Arjuna meeting Maha Vishnu, the commentary is brief. This is screenshot of Viraraghavacharya's commentary.
The acharya interprets that kalavatirnau in 10.89.58 not as My expansions but as kalaya avatirnau that means the two who have descended with kalas(potencies). He says Krishna is poorna avatar. He didn't elaborate on why Vishnu stole brahmanas year after year to see Krishna.
And in 10.89.62 (63rd verse in SS) he quotes bg 7.8 (śabdaḥ khe pauruṣaṁ nṛṣu) to explain second half of the verse. I think what the acharya says is that by Krishna's grace, Arjuna got the ability to see the Vishnu's abode.