That's why the rule should be:
NO GUNS ON THE PLANE. PERIOD.
Interesting logic. Using this reasoning (no pun intended), let's also search today's papers for drunk cops, drunk air marshalls, etc.
What the guy did was wrong, period. Nonetheless, I think we can still safely say that anyone bringing a box cutter to a gun fight would have been met with dramatically different results on 09/11.
(I hold a CDW license that's valid in 26 states and I'm currently looking into getting an NYC permit. )