I think the point is, that there should be a transition period of “limited government” - meaning - that within a new society wherein people are weaned off their tendencies toward violence (by means of channeling their focus toward voluntary-volunteerism), there would be a form of benevolent-militia who would apprehend all those who are not sticking to the non-aggression principles.
Such people would ideally be transported to a fortified (albeit benevolent) island, and perhaps taught to channel their violent streaks into productively farming plots of land on that island or whatever outlets are most suited to any particular “convict”.
As for the extremely-brutal blue-collar (or psycopathic white-collar) criminals among them, I’m clueless as to how they should be dealt with. The world has become very complex and scary.