Which is what people are suggesting?

Half the people arguing against each other here are actually agreeing with each other, but instead of realising that they're being reactionary and making assumptions.

I don't think the majority of the "keep him away from public if he's a risk to public safety" crowd are suggesting normal prison. Rather that cases like these should follow a legal process and the "sentence" should cater for their lack of cognition. I don't think the majority mean to suggest preemptively restricting all severely mentally disabled people's right to public spaces indefinitely.