We cannot allow our last defense of the Aircraft to be at the Gate. We cannot. Neither can we allow the Line to be at the Cockpit door. Any ruthless and suicidal jerk will at least think of his demise in logistical terms were he to believe firepower of this sort is his destiny. Denial of reality begs disaster.
What a load of bull... Keep up that paranoid obsession, and you'll end up just as bad as the ones you want to keep out...
Guns on the flightdeck have not, and will not solve anything...