In only 15 years of listening to pilot stories, I remember 4 different first hand accounts of how pilots got injured while trying to solve a Pax problem in the cabin. The one I know best has been wearing a very nice set of third teeth since the incident...
My 2 cents: our duty is to operate the airplane until a safe full stop on the ground. Anything that compromises our ability to do so should be avoided.
Thus, I don't care how much of a wimp I look to my cabin crew: neither Pic nor FO will leave the cockpit if things get physical in the cabin, and the door stays locked. Period.