@mmmfeet Not going to take a chance that he is still capable of pulling the trigger while holding a gun or a backup gun. Emptying the clip DOES neutralize the threat of someone threatening to kill you.
If the state is going to press charges against you for defending yourself and the thug's family is going to try to sue you even after only the first single shot fired, you might as well make 100% sure you are safe in the heat of the moment with an empty clip.