As I discuss in the this answer, by far the most popular school of Hindu philosophy is the Vedanta school, which bases its tenets on the doctrines laid out in the Brahma Sutras, a work by the sage Vyasa which summarizes and systematizes the philosophical teachings of the Upanishads. You can read the Brahma Sutras here. In any case, Adhyaya 3 Pada 3 of the Brahma Sutras describes the Brahma Vidyas, 32 lessons found in the various Upanishads which can each lead you to Brahman if you meditate on them. You can see the full list of 32 Vidyas here.
Now as I discuss in my questions here and here, one of the 32 Brahma Vidyas is known as the Panchagni Vidya, and it is found in the Brihadaranyaka and Chandogya Upanishads. Among other things, it describes the path of souls to Brahmaloka. Here is how the Brihadaranyaka Upanishads describes this journey:
Those who thus know this, and those who in the forest worship faith and the True, go to light (arkis), from light to day, from day to the increasing half, from the increasing half to the six months when the sun goes to the north, from those six months to the world of the Devas (Devaloka), from the world of the Devas to the sun, from the sun to the place of lightning. When they have thus reached the place of lightning a spirit comes near them, and leads them to the worlds of ... Brahman. In these worlds of Brahman they dwell exalted for ages. There is no returning for them.
In his commentary on the Brahma Sutras, Adi Shankaracharya argues that the "worlds of Brahman" being referred to here are merely the worlds of the god Hiranyagarbha or Brahma, not the supreme Brahman, because it's impossible to "go" to the supreme Brahman, since it is omnipresent. In the course of this discussion, Adi Shankaracharya says this:
When the reabsorption of the effected Brahman world draws near, the souls in which meanwhile perfect knowledge has sprung up proceed, together with Hiranyagarbha the ruler of that world, to 'what is higher than that i.e. to the pure highest place of Vishnu. This is the release by successive steps which we have to accept on the basis of the scriptural declarations about the non-return of the souls. For we have shown that the Highest cannot be directly reached by the act of going.
By the "highest place of Vishnu", I think Adi Shankaracharya means Moksha; here is what he says in his commentary on the Katha Upanishad:
The man of knowledge attains 'the highest place of Vishnu', i.e. the nature of the all-pervading Brahman, the Paramatman known as Vasudeva (the Self-luminous).
So my question is, why would Adi Shankaracharya use "proceeding to the highest place of Vishnu" as a metaphor for attaining Brahman, in the midst of discussing why an Upanishad passage that talks about proceeding to the world of Brahman is not referring to attaining Brahman?
Is Adi Shankaracharya intentionally doing some kind of word play, composing a passage that uses the metaphor of "going" to the place of Brahman in the midst of discussing another passage that talks about literally "going" to the place of Brahman? Have any other Advaitins commented on this?