Probably doesn't pay as much as a feature film movie role in a JH Abrams Star Trek film. I doubt his agent would be interested as it would dilute is earning ability with respect to Star Trek ( IE he's willing to take less money to play a Star Trek series roll as opposed to a feature film roll.)Probably. Probably pays well.
You're not going to be seeing any of the cast from the proposed j.j. Abrams Star Trek 4 film appearing as another character on Strange New Worlds.
It would just be very expensive stunt casting, and probably not conducive to using the character a lot in SNW Spock's character arc.