This has nothing to do about him "being ready" this has everything to do with dedication to winning and pride of repairing his damaged reputation. Voluntary's are NOT voluntary for characters/players like Marshawn. He has everything to prove to Buffal and the fans about his dedication to the team the city and the fans.
All this is doing is proving to everyone that Marshawn is scum of the earth.
but I don't care what marshawn thinks or does anymore... He'll never be a great RB, he obviously is undedicated to that process.