He's not endangering his life, he doesn't have "brain damage", he had a concussion and was treated for it, he took two years off, and has since been cleared by the finest doctors in the United States as being fit and able to fight. I'm not really sure where you are getting your information but it's a bit flawed, it would seem.
He's fighting at 160...part of the problem was he got lazy and went to 168 so he didn't have to "cut weight" and/or train as hard/as long.