Here is the ending of the second-to-last entry in Unqualified Reservations by Curtis Yarvin (AKA Mencius Moldbug)[0]:
> Anyway. UR will reemerge, of course. But not here, and not soon—and probably not even in this form. I’ll also try to do something non-lame with the archives. Thanks for reading!
If the name alone isn't enough, I feel like this context makes it pretty obvious that he named Urbit after his racist blog.
He claims to have been working on Urbit since 2002, and the first UR post was from 2007. It's entirely believable to me that the name Urbit came first (albeit not publicly), but the names are very obviously related and the quote I pulled above shows that he considers some post-2014 project a continuation of UR. I can believe the specific claims of the comment you linked, but I think it dances around the fact that these two projects are purposefully tied together by nomenclature. Whether UR or Urbit was named first in Yarvin's head isn't really the point.
> Anyway. UR will reemerge, of course. But not here, and not soon—and probably not even in this form. I’ll also try to do something non-lame with the archives. Thanks for reading!
If the name alone isn't enough, I feel like this context makes it pretty obvious that he named Urbit after his racist blog.
[0]: https://www.unqualified-reservations.org/2014/08/hiatus/