I really don't like the idea of keeping people in boxes, and agree that even in the case of the most wretched human being I'd rather have them free and alone than locked in a box without a goal besides punishment. However, this man's crime was human trafficing. Do you really want a human trafficer living in the woods like some kind of troll monster, ready to capture more children? That sounds like it could potentially result in more captive humans, rather than less.