There are two counter arguments that i found while reading the Yajnvalkya Smriti.
The commentator Vijnashwera in his famous commentary "Mitaksara" discusses and refutes these two arguments as follows (go to pp168 of the PDF):
Objection1:
An objection:—The rule of Sati does not apply to Brahmana widows.—But
there are texts (says an objector) which prohibit (Anugamana) (satism)
for a Brahmani woman, such as :—" There is no anugamana or
self-immolation for Brahmani woman ; for this is the command of
Brahma. But among the other castes this anugamana is said to be the
highest austerity. (Their duty is) to do their husband's good, while
he is living ; and to commit suicide when he is dead. But that woman
of the Brahmana caste, who follows her dead husband (by anugamana)
does not lead either herself or her husband to heaven because of the
sin of her suicide.
to which the reply is:
Reply,—To this we reply that these and several other texts, relate to
the ascending of a separate funeral pile, because of this special
Smriti : —;" A Brahmana woman cannot follow her husband by ascending a
separate funeral pile." From this it follows, that the women of the
Ksatriyas and the rest are allowed to ascend a separate funeral pile.
Objection2:
Another objection, -Some, however assert :— ** Because suicide is as
much prohibited for women as for men, therefore, this direction for
Anugamana (satism), like Syena-sacrifice, is meant for those women
(only) who through inordinate love of enjoying heaven, transgress a
prohibitory rule of law (which forbids suicide), just as :— " By
Syena-sacrifice let him kill his enemies," is a direction for
Syena-sacrifice given to those, whose conscience has been overpowered
by constant thinking (bhavana) over this doing of injury and by anger
(revenge)."
and to which the reply is:
We say this is wrong. Because it has been described by some that
Syena-sacrifice (hawk) is injurious on account of its fruits ; because
the conception (bhavana) which is to be accomplished through the
instrumentality of the Syena-sacrifice, and whose effect is injury of
others, wants the sanction of law (because there is no Vidhi to the
effect : —Thou must kill thy enemies :) but (on the contrary) there
are prohibition (thou must not injure anybody, not even thy enemies).
According to their opinion, because injury (to one's own self here)
being a means to attain heaven, is commanded by the law relating
scriptures (Sravana) pondering over their meaning (manana), and
realizing their sense (nididhyasana) by meditation. Therefore, life
should not be cut short, for the sake of obtaining *' heaven," which
after all is but temporary, and whose joys are small. This is the
meaning. Therefore, for the woman, who wishes not Moksa (emancipation)
and is desirous of getting heaven, which is not permanent and of small
happiness, Anugamana is proper ; like other Anusthanaa (religious
performances) for the attainment of particular desires.
Therefore, nothing is blamable : (both views are correct : suicide for heaven or living for others)