Nah, you guys just don't get it... still.
The gun is nothing but TIME. combined with the door, the two of them MIGHT buy you enough time to maintain controll of the aircraft untill you reach the ground and turn a potential cruise missile into a building.
If you lose controll of the cockpit you will (at best) be shot down.
That is the whole point of the excersize. Its not to have anything to do with the cabin. Its to keep the cabin from coming into the cockpit.
9/11 didn't work once. Its worked 4 times that day. I see the results of it everyday. The VERY worst that could happen with a gun in the cockpit is you could accidentally kill the pilot sitting next to you. Its extraordarily unlikely. But you know what? We already decided its okay to have dead pilots at the controlls. Otherwise we never would have raised the retirement age for pilots. More pilots will die at the controlls from the increased retirment age, and thats a FACT!
If you want to do away with the guns in the cockpit, the solution is simple. Absolutely no access from the cabin to the cockpit. Give the cockpit its own external door to the airplane. A solid bulkhead between the two with no door what so ever. Not on the ground or in flight. Then you don't need the guns in the cockpit and I will be the first one clamoring for the removal of them.
However, you aren't going to get to stand in the doorway and say goodbye anymore. You could run up to the terminal though and wave as they come off the jetbridge if your ego needs the stroking.
Cheers
Wino