I just hope he doesn't get charged, he'll have a heck of a time proving he was actually in fear for his life. Neither robber showed a weapon of any kind. Lot's of potential problems with this one. If he had just whipped the guys ass probably wouldn't be a problem, but just the law suit the thief is going to hit him with will be expensive. Hope I'm wrong, but don't think I am.
Yes, he's in for big trouble, unfortunately. No lethal force permitted in the law short of an actual attack on him (or someone else), or an imminent threat of same. There should be a carve out in the law permitting lethal force when someone, with criminal purpose, jumps the counter from the customer area into the employee-only area. That should mark where all bets are off.