Isn't an inpenatrable door called a wall? Doesn't every door have to be penetrable somehow? I agree that we should make the doors as strong as possible, but a door has not been invented yet which cannot be opened. If you can come up with one, I'll be all for it. In the meantime, we should have one extra layer of safety, a surprise waiting on the other side of it should it be breached.
Speaking of immature statements, who ever said we intended to come out of the cockpit to play "John Wayne?" Your statement, while immature and argumentative, also displayed a stunning lack of knowledge of the guns proposal. No one has ever suggested we come out of the cockpit to fight. That is the marshall's job (I hope we get thousands of them). However, on the outside chance the bad guys get past the first lines of defense (security, marshalls, f/a's pax, cockpit door, etc.) I would certainly like to be able to defend myself. Or would you prefer getting shot down if terrorists get into the cockpit? That's what the choice will be if they get in...They die, or we all do. Why shouldn't we do everything in our power to increase our chances in the event we ever have another fight to the death in a cockpit?