It'd have to be one of those split-second judgement things. If, at that moment, I thought he was a genuine threat, I'd step back and shoot him where he stood. If, on the other hand, I thought he was just a shakey jackass, I'd permit him to live and might even give him the money. I've yet to have the employer I loved so much that I would kill or die to protect $50 of their money.
"No honest man needs a handgun smaller than a canned ham."