I think the interesting debate here is whether he can survive 10 years probation on his own...maybe no direction without football, may start drinking again....or whether a team structure helps him stay clean. I can see arguments for either. Honestly though, I think you are playing with fire if you keep him and another incident happens. I just, looking at him as a human, hope he can get things straight and be happy with the leniency.
One of my frat brothers was in the same situation. Fell asleep at wheel after drinking, killed his best friend. Got probation, went to TCU. Good guy. Years later, drinking and driving again and rams the back of a car at 3 am. Kills another guy. Gets hard time. Probably out now. But even the best people have issues that you can't control.