Highvolt,
While what you say may be true, if he has already made it into the cockpit to take the gun, the pilot is no worse off than he would have been, and atleast he had a CHANCE to defend himself.
Pax screening will never work. In prison where convicts have NO rights and regularly submit to strip searches and worse, they get knives all the time to fight with.
Saw a flight attendant yesterday carrying around a plastic knife for protection (this was a real weapon, not a plastic eating utensil)
Armor the cockpit, provide guns incase the armor fails. The armor will provide enough time for the pilots to pull out their guns and shoot anyone that makes it through the door.
Cheers
Wino