Saying that all short women have bad tempers is like saying that all redheads are crazy, or that all men cheat.
Just because it seems to be frequent in YOUR experience does not make it a universal case.
On the other hand I have had a theory of the "Chihuahua Syndrome" And that involves people of lesser statures being more volatile, hostile, and confrontational. As in their bark is bigger than their bite. I feel that they have to do this to ATTEMPT to regain some imaginary power that they absolutely NEVER had or will have.