"I was a little scared at this point. I was yelling clear commands. In that instance, I fired a shot over his head and he froze," he said.
Hmm, I wonder where that shot went? Not the best example of the defensive use of a handgun. Why not just call the cops, since there was no threat except to the business owners insurance company? Be a good witness if lives are not at risk.
At any rate, Pry Bar=Lethal Threat=Shoot to Stop.
That would be the Indicated Response.
Only problem is that there is also an explicit duty to retreat unless the act of retreating will place you in more danger than if you had stood your ground in the first place. He allowed him to advance until there was a threat.
I think he should've followed your advice and just been a good witness as you said, there was no danger to life and limb until he got within striking distance with the club.
NEVER FIRE A WARNING SHOT!!!