Showing your id does absolutely nothing to prevent weapons from getting on the plane. If you are so dangerous that your mere identity is enough to prevent you from getting on a plane, then you need to be arrested.
Identity is extremely easy to fake. If you are planning in such a way that you have a realistic chance of hijacking a plane, getting a fake ID good enough to fool the two-second check at the TSA checkpoint is the least of your problems.
There is some argument that a properly built luggage and human screening system could actually prevent weapons from making it on the plane. But ID doesn't really come into it.
But even if we can't develop a system that prevents weapons from getting on planes, it doesn't follow the id checks would be a suitable alternative.
