I think it's also important to get across to him that he doesn't get to pick his consequences. He gets to make his choices but life doesn't let you pick your consequences. You love him too much to let him grow up thinking he has this kind of power.
Hope the trial run works out and I'm impressed with his reasoning. I've had similar experiences as Kriston with problematic behavior when DD's computer time is over. The consequence is a break from the computer and she usually asks (screams!) for a different consequence. I stay firm with the original consequence because I don't want her to think she controls her consequences. DD is usually very upset when she wants a different consequence but if she approached it like your son did, I might reconsider the next time.
