This is a real close one, but overall I agree that rehab was a legitimate, albeit gutsy, option.
Rice's behavior was unacceptable and way overboard. But, as a result, he was reprimanded, suspended, fined, and sent to anger management. It's unclear as to whether or not they were monitoring his progress during the season, but I think that should've been done as well. In the event any of the behavior returned, it'd be immediate grounds for termination. Again, this is a real close one, and I could've also seen merit in firing him from the onset.
I don't think the AD should've been fired, though, for trying to rehab the guy.