If the terrorists can't get through to the cockpit, then what is the problem with the pilots being armed, particularly if, as even you admit, they have the appropriate temperment for handling firearms.
Simply put, if the guns are in the cockpit, and the terrorists can't get to the cockpit, then there is no problem with the pilots being armed. Conversely, if the terrorists can get to the cockpit, then the pilots should be armed because they will be the thin blue line in the sky which stands between us and another 9/11 atrocity. So no matter how you look at it is a no brainer as far as the pilots being armed.
For people who take the former view, it only stands to unreason that pilots should not be exposed to an object that will slowly corrupt its bearer, like the One Ring.