I was asked to give further input in light of the thread’s responses.
(
TL;DR - I still disagree with individual
Universes being 2-A as I find the evidence for this extraordinary claim to be lacking and built on assumptions. The overall
Multiverse being 2-A, while non-definitive for reasons the OP pointed out, is feasible based on the Infinite Timestream statement, thus warranting a
“Possibly” rating in my view. I also think Dr. Holiday’s claim at the end of the crossover can work as supporting evidence for the multiverse’s size, albeit I’ll explain why I find it to be shaky by itself)
After reading the whole thread I’m still not on board with the universe being a 2-A structure, and do not see the Twitter questions as viable given that some conflict with each other,
which to my understanding means information from the actual series itself should be prioritized. An explicit statement (not assumptions) from the series that the infinite dimensions are part of the prime universe was not given, so it doesn’t seem the burden of proof was fulfilled on that front.
Regarding Dr. Holiday, I’d say her assertion that there are infinite dimensions is her speaking theoretically rather than taking it as 100% objective confirmation, as she lacks Cosmic Awareness or the means to deduce the full scope of the multiverse (evidenced by her not even knowing the multiverse was real prior to the crossover). Regardless of how “smart” she is, her initial ignorance of the multiverse’s existence does cast doubt on the claim that she randomly attained an ironclad answer of the multiverse’s scope. She was made aware that the multiverse exists due to the events of the crossover, but how would she know for certain that it’s infinite? And no, being a genius scientist isn’t enough to say she knows for certain how big existence is. Scientists are not omniscient and can be wrong, even in fiction (evidenced by how Dr. Holiday literally said something wrong in the crossover).
Regardless, Dr. Holiday’s theorizing could be feasibly corroborated with the infinite timestream statement, which is why I’d support a Possibly rating.