It goes without saying that David Garza is a hero.
No matter how you slice it, if Garza didn't have a gun, this altercation would have ended differently. It's likely that this fifteen-year-old girl would have been sexually assaulted. If Garza didn't have a gun, any direct intervention would have been far more dangerous for him.
This is also a defensive use of a firearm that won't show up in crime statistics. No shots were fired. Nobody was injured with a gun. This is what most defensive uses of firearms look like.
This monster wasn't looking for a fight. This asshole picked didn't choose a fifteen year-old victim in the hope that he could show off his Krav Maga skills against a worthy opponent. He wanted a victim who had no chance of turning the physical altercation around on him.
The gun stopped the assault.
Don't give me any "Call the cops." bullshit. You wait for the cops, and this monster has another solid five to ten minutes (or more) to do whatever he wants to that girl. You take the gun away, and you have another rape victim or worse.