You're all wrong. It's Lazarus. Just wait and see. Alternate reality. The Alternative Factor. Iconic first season character. Don't like the lack of a wispy beard, though. Clear canon violation there.
It's possible. it could be that the detonation of the Red Matter by Spock prime in the last movie somehow disrupted Lazarus in his normal reality. Maybe in the movie Lazarus meets his alternative self for the first time creating a catastrophic circumstance that causes the fleet to be 'detonated'. I like it.