Are German prisons that nice? Or is he that sorry?

He has a roof over his head, and gets fed. It would be much harder outside then to remain inside. The world as he knew it has completely changed.

True, but still!

There's also the physclogical thing that comes into play here. He's in his late fifties, has no skills. The only *family* that he has created is in the prison. Remember *shawshank redemption*? I imagine that he is very afraid of the changed world that they want to push him out into. It's easier to stick with what we are familiar with, no matter how bad it is.