A Glock has how many in the clip? Why fire only one round?
Anyway, good story with a happy enough ending.
Didn't see a sarcasm not so wasn't sure if you were serious.
There are two schools of thought. One is based on what may happen in the courts and is geared toward applying the least amount of deadly force that will resolve a "situation."
The other school of thought is based on combat and sometimes the courts and that is to keep firing until there is no more ammo and the treat is totally destroyed or gone. Sometimes the "I was so scared for my life I just pulled the trigger and didn't realize that I kept pulling the trigger until the firearm was empty" is both a classic sign of stress and a great argument in litigation.
Considering that the man's son may have been in the general direction of the firing, the store owner may have opted for the approach that minimized the potential harm to his son for a slightly off-target shot.