Very very tough on Sully here. He is a talented young player, only 24. He'll be inexpensive and he'll have a less major role on a team with Al Horford (and maybe Okafor).
I understand the frustration with his weight but Sully off the bench for 15-20 per night (more/less depending on match-ups) sounds ok to me. Horford and Amir providing professional role models. Many people have a maturity spurt around 25 -- it's possible. At a bargain price and with all practical motivators in place, it seems like a reasonable thought to bring him back. It's obviously not the only acceptable option, but I think it is definitely acceptable.