he has a liz franc injury and they don't know when he will return.
also his days of being a pass rusher seem over. As a five technique playing on the strong side vs the run he is still pretty good. His long arms are a huge asset.
They are not trading him because of the injury but they wouldn't even if he wasn't. Jerry doesn't trade players like him. He only dumps players who do something that he gets mad about on a personal level, like jay ratliff yelling at him in the locker room or amari cooper seemingly not giving his best effort in road games.