Captain Robert April wrote:
And that prevents him from choosing to go back intentionally to fix all this....how?
It's simple. Slingshot around the sun to go back to a point before the timeline diverged and prevent the destruction of the Kelvin, presuming that's the focal point in the timeline (another argument), then go back to the point in the timeline before this whole thing started, apparently the destruction of Romulus. Prevent that, or at least mitigate the results somehow, to the point where Nero doesn't go on a time-spanning rampage, and bingo, timeline restored.
But then, JJ wouldn't have his own Star Trek universe to do with what he wants.
You have no idea what you are talking about. soon as he is accidently thrown back in time nero attacks him (Nero knew where and when he'd end up and waited for him) and takes his ship and leaves him to die on Delta Vega.