Well here's something to consider: if one insists on believing that this is the original universe altered then you have to accept that everything previously in Trek has been wiped clean and is irrelevant.
Unfortunately, it pretty much is irrelevant.
However, no you don't, you can just accept that in this particular instance time travel works differently as a result of magic, sorry, red matter.
There are always... possibilities.
Besides, isn't the argument for it being the original universe altered a different one from Spock being TOS Spock or not?