Two points here:
1) If you are trained PROPERLY in the use of fire arms, you would never pull a gun so late in an altercation. I've pulled mine twice. Both times the assailant was 20 yards away! Why would I allow someone who I feared get so close? I wouldn't. Unless I was chasing him and rounded a corner right in to him, but I don't chase people when I'm carrying. Fuck, I don't even run when I'm carrying. Why?
2) If any of my children decide to carry a fire arm, I feel it is MY duty as a father to instruct them on when and how. CCL classes tell you the laws and how to fire/clean a gun. What they don't cover is adrenaline dumps, emotions, Etc. The real question is, if Z was NOT armed, would his actions have been different? We all know the answer to that one.