What is the purpose, then of the lock? Is it to disable the firearm at a certain time, or to prevent it from being deployed at a certain time, or what?

Regardless the purpose, I can think of far better, more effective, and much safer ways to accomplish any/all of the above.

That lock has to be one of the most ridiculous ideas I've seen in quite a while. I put it in the top three all time for idiotizing an otherwise great idea for the use of a firearm.

I can't think of any condition in which I would ever carry a firearm like that. I would rather do without, and I abhor being disarmed. I have to think it would be preferable to remain unarmed and come up with a different strategy than to be armed but unable to use the damn thing.

If the government were really concerned with secruing that cockpit, then they would deputize the cockpit flight staff. I can't imagine airline pilots being somehow less capable than the average joe they pick up off the street to turn into a sky marshall. It's not like their criteria was all that stringent. In many cases you are talking ex-military for flight crews.

Another example of bureaucracy getting in the way of good sense.