Why would he possibly want to stick around and rehab here when he can go home and have it all payed for, hang out with friends, and have his mom cook him dinner? He wasn't going to be resigned by the Blazers next year anyway, and he has his paycheck for the year, so he is basically out nothing long term.
It is rare that second rounders that remained in the second and third unit ever get a second contract, and unfortunately for Jeff, nice guy as he was, that is the category he falls into.
It would have been wholly irresponsible to get rid of a serviceable player and keep him around now that there is no IR, people would have Cho's head once another injury hit and we didn't have enough players.