No legitimate professional, Law Enforcement, or Military weapons training endorses or even condones "warning shots". A weapon is meant to stop, subdue, and kill an assailant. In this case that's what it did, as it should have.
If I decide that my life, property, or family is in jeopardy and I draw my weapon somebody is going to die. I don't take prisoners and I don't call 911 while the perp has a pulse.
It’s not a good idea to voice intentions that could be considered premeditation on the internet. No matter how confident you are that it could never be connected with your real name, and that you will never be involved in a self-defense shooting.