On September 11th, our president could have gone on national TV and said, “I call upon all armed citizens to load their weapons, and go outside to secure their communities against terrorists. Under the emergency powers granted to me, I hereby suspend all federal[,] state and local regulations against the possession and carrying of firearms.” Large chunks of the US would have been safe from terrorists. Then the government could have concentrated on the disarmed bits like airliners and so forth. Make their job much easier.
And Senator Feinstein would screech about state sovereignty; that’s worth a heap of bonus points.