Spock and Uhura don't really know
anything. This debate is pretty inconsequential, but that they guessed it was an alternate reality doesn't conclusively tell us what it was an "alternative" to. Obviously, Enterpise
still a part of this reality -- so all of the events of Enterprise
are, as well, even the time travel elements. This theory seems pretty good to me -- there's nothing in Enterprise
to suggest which Captain Kirk it is that Daniels came after.