I couldn;t agree more with you, Benjamin, but, as I said, there's a madness to their (TSA's) method:

The airline pilot is not a trained law enforcement officer. Yes, many of them are ex-military pilots, but the preceeding sentence still applies. The TSA has trained them well enough to (hopefully) protect the cockpit. In the eyes of the airline industry, the cockpit is the key to the safety of all the passengers. Some passengers may get harmed, for example, in their seats or in the aisles, but ALL will be harmed if the cockpit is breached and won.

So.....their reasoning is: the pilot's job is to fly the plane. THat's all, just fly the plane safely. In order to ensure that they can do that from point A to point B, they must have a secure cockpit. Whatever happens beyond the cockpit door is not their concern (sounds terrible, I know, but they have a primary function that cannot be interferred with), beyond the cockpit door is the concern of TSA Air Marshals, other armed officers, and well-abled passengers. Now....

....once the plane lands and is secure, the pilots can exit the cockpit. At that point, as someone pointed out, they don;t want untrained personnel (pilots) carrying firearms that are not secure and could be taken from them. By untrained, I mean what they mean: ex-military, weapons-trained, highly capable people who are NOT trained in all the aspects of law enforcement.

I know it sounds a little crazy, but this is their reasoning, for whatever it's worth. I'm speaking here, not from "the inside", but from close enough to eavesdrop, if that makes sense.

The fact is, an accidental discharge occurred. Even if pilots were allowed to carry firearms, unlocked, whereever they went, accidental discharges will occurr, from time to time. So, regardless of the TSA policy to lock firearms, it has nothing to do with ADs. Now, the way they're required to lock the firearm and the devices used to do so, are of course relevant to ADs.