The question is what constitute a threat? His behavior did not merit detainment. He broke no laws. Look, this is not rocket science. Designate ISIS(or whatever we call it this week) a terror organization and pass a quick law prohibiting Canadians from belonging to such organization, then nail returnees on their way back. Chances are, when facing a dime, they'll elect to stay in the war zone maybe even die there. Win-win, if you ask me. Instead, we're keeping them here, have no means to control them and we abuse our fundamental rights. And for what? What threat does such animal pose to Canada and his fellow citizens in Syria or Iraq? He's just another inexperienced body in a meat grinder, unlikely to survive the conflict.