Obviously there are a number of reasons why passangers act in a disruptive manner and a number of threats they represent.
The reality is that in many cases it takes about a 10 seconds intevention by the Captain to convert the trouble maker into a meek&mild non event. In the pre 9-11 days it would have been viewed as a very standard way of dealing with the problem.
Of course this doesn't detract from the current situation where we have to assume it's a decoy for a greater threat so flight crew should no be leaving the flight deck in these circumstance. But those that are saying the Capt will have no better ability than the cabin crew to control trouble makers are pretty ignorant.