I would not release him, there's always the chance that you could introduce exotic diseases and bacteria to wild populations especially starting with terrible conditions. But that's not what I would be worried about, I would be worried about the animal not being able to find food. And I am also very anti-exotic release into wild populations, I don't know much about which turtle is from where, so I don't know if you have yellow bellies naturally in your area, but personally I wouldn't release it. I'm not going to preach to you, but florida has enough problems with exotic release from irresponsible owners, so trying to be responsible and give him space would not be releasing your pet somewhere.