Using your hypothetical example as a basis for your math, the only thing you proved here was that 2^t isn't the largest number of timelines and that 2^(t+1) is bigger. How you got that to mean there suddenly isn't a finite number of worlds anymore, but infinite ones, is entirely beyond me. This only means 2^(t+1) is an even bigger expansion of finite worlds than what would be given to us from 2^t. Not that it suddenly jumps from finite to infinite.
I suppose I should explain Greenshifter's argument a bit more in-depth (or at least my understanding of it), hopefully it'll clear out some confusion.
Basically, the math he wrote down is pretty much supposed to be a
proof by contradictio, where the validity of a proposition
P is to be proven by showing that the the opposite assumption (
P is false) leads to a contradiction, and thus making us default back to the scenario where
P holds as a valid proposition.
In this case, the infinite timestream (t) is assumed to have only a finite number of parallel timelines branching off of it, the number of which is identified by 2^t (
the set of all possible permutations (branches) of the timestream.) The contradiction here would be that, if the timestream is infinite, then 2^t (under the assumption that it is finite) would not truly be the set of all variations each moment can take, as there would always be another moment (+1) which can branch off into another possibility, and endless moments after that one as well. Thus, 2^t being a finite set is a contradiction, and we then head back to the proposition that it is infinite.
In plain english, it basically boils down to the argument that a timeline that is infinite in length can't have a finite number of possible permutations which each event in it can take.
However, my issue with this argument is that it seems to be making an a priori assumption that all possible timelines that branch off from the primary timestream are already instantiated into existence in the first place, instead of timelines constantly separating from the main universe in a successive manner ad-infinitum (on and on).
Greenshifter compared the counterarguments against a 2-A multiverse to saying the set of all prime numbers can't be infinite because each prime number is finite. I'd say that's kind of a shady comparision, since number sets are conceptualized as collections that are already completed from the start, as opposed to ones that are comprised by continuous additions of members. For instance, the integers aren't constantly popping into existence when we address the set which contains them, they are all already there.
What Ben 10 describes would be closer to the idea of "
potential infinity", if anything, as the timelines are constantly multiplying in number instead of all possibilities already existing simultaneously, as I've said
and there's also the fact this would be Low 1-C if legit, not 2-A, but we're not gonna talk about that