Yeah, the question of what to do with people who truly cannot play nice in society is one I’m still learning about re: restorative justice and prison abolition. There are a small number of people who are just irrepairably anti-social and I’m not sure how you’d deal with them. Sending them to a rural area or colony where their movements can be tightly monitored while allowing them some degree of freedom within an assigned area is the best I can come up with.

In Iain Banks The Culture, iirc, people who commit serious crimes are assigned a drone that follows them around for the rest of their lives. They’re allowed to go anywhere, do whatever, but if they try to do something anti-social the drone will incapacitate them. That’s as close as they have to a prison system.