'Orbital skydiving' was a scene added to the script to appease Shatner's concerns that Kirk wasn't integral to the earlier drafts of the script, and to get him to sign on to the movie. I've a theory that the film-makers never
seriously intended to actually use it, but having shot the scene they had pleased Shatner, and they could still turn around to him afterwards and say "Well, we tried
to work it out in the editing room, but it just didn't make the cut".
I certainly can't see how it could be reinstated without making the opening of the movie bloated.