Here are his contract details: http://www.spotrac.com/nfl/buffalo-bills/aaron-williams-7749/
That's tough. He could be designated a June 1st cut and the Bills would be hit with cap hits of $2.45M in 2017 and 2018. If he's kept for 2017 and released before 2018, he'd have hits of $6.625M in '17 and $2.45 in '18. If he plays out his deal his hits would be $6.625M in '17 and $6.825M in '18. Those are some big numbers. He's worth it if he can stay healthy, but he's also a huge injury risk. And it doesn't help that he's about all we've got at safety.
Honestly I think this comes down to two things: 1) what the doctors say and 2) whether or not the Bills are rebuilding or are pushing for the playoffs in 2017. If they are in rebuild mode, then they should release him. If they're pushing, then they are probably better off taking the chance with him for at least 2017.
Yeah, I agree. As a fellow human being I hope he either retires on his own or gets retired by the league before (further?) permanent damage gets done to his brain.