I don't think it would make enough of a difference to change the outcome, (which we don't know yet). I predicted Boston in 4 or 5, and I wouldn't change that prediction if Bynum were playing. The Lakers are just so weak defensively, and the C's so much better defensively, that I think they're far out-matched.
No offense or superstar in the world can overcome a great defense like the Celts, (when they're on). As I've said before, this is up to the C's to win or lose, and how badly they want it. Whe they're playing their best, no one can beat them. How consistently they play well is the key.