Here's the problem--this was where the writers had the chance to put works in the characters' mouths and actively chose not to do so. The only language used was "alternate reality." But if I travel back in time and wipe out the prime universe, of course the new timeline is an alternate reality. That line means nothing for proving the prime universe still exists.
As for the writers' intent. If Ron Moore and Brannon Braga did a joint press conference with Rick Berman and William Shatner, and they said, "we declare that Kirk did not die in Generations and Picard was just building a rock pile because he was bored," that would not change a thing.
I think your example is flawed because we DID see Kirk die in Generations. There is direct visual evidence to the contrary. In the case of Star Trek (2009), the writer of the movie said this is an alternate reality and there is NO evidence in the movie to suggest what he is saying is not true, it fits what we saw on screen.
But if you want to believe the prime universe was wiped out, that all of the original series, TNG, DS9 and Voyager never happened, have at it. In your case all that is left is Enterprise. Enjoy
