Cute gag - the NRA would not "insist", and would not suggest "open carry" for tactical reasons either. To top it off, guns were allowed to be carried on board US airplanes till the 60s.
What are the odds that more than half of the passengers want to die in a terrorist strike?
So if we equipped all passengers with tasers, all terrorists would be caught. Of course, sometimes there might be some minor accidents, but they're not (very) lethal or harmful to the aircraft structure.
One change would result. You would have to pay the cabin attendants a lot more :) Also the safety instructions would take a while longer. They would show how to operate the taser in case your neighbor starts doing something suspicious.
BTW if you let all passengers have them, you'd be arming terrorists, sooner or later - all they have to do is use it on a pilot going to the bathroom, if they are ready to die they don't need anyone to land the plane.