Set Harth wrote:
If he was Mitchell, wouldn't Kirk recognize him?
Why? Kirk went to the Academy three or four years later than he did in the Prime Timeline.
Kirk and Mitchell knew each other in this timeline as well, and Mitchell died. It has been covered in the Ongoing comics, which are supposed to be more or less canon.
And even if they weren't, I doubt that Orci as a creative consultant would have greenlighted the comic if he had such a radically different story in mind for the movie. Even if Mitchell came back from the dead, Kirk WOULD know who he is.