So, Pandora, when the terrorists, intent on suicide, pushes his way past all the unarmed passengers on to your flightdeck, what do you propose to do. Poke his eye out with your ballpoint, maybe? When he has taken control of your aeroplane away from you, because you had no means of opposing his knife, will you walk sheepishly to the back of the aircraft, to be tied up, as were some of the crew on 11 SEP. At times like that you would regret not having had a gun in the first place.
Will the discussion move up a gear if they manage to pull a similar stunt, or are we all assuming that lightning will not strike twice.
As for Joe Public worrying about armed aircrew, would they rather a pilot had the means of preventing the suicide dive, or would they rather wait for the Sidewinder.
For those who feel that they would be unable to pull the trigger, there is not much I can say. However, that is no reason for denying the opportunity to the rest of us.