I wouldn't be too concerned about it. It may take awhile for the hormones to regulate.
I do think that after two weeks he shouldn't be swollen. I have never had one do that. As a matter of fact I never noticed any swelling. Maybe I'm crazy but I would be more concerned about that. You say he is still a good bit swollen?
Has anyone else's cat been swollen two weeks after a neuter???
I'm not trying to scare you, its just that I have not had that happen to any of mine. I'm curious because I'm taking my last two boys for neuter next week.