“I’m betting the hero gets fired.”
I am hoping not. This is not a situation where the clerk opened fire as soon as the perps demanded money, or chased them down after the robbery. Here they were beating one clerk and herding them towards the cooler which, to me, can be reasonably interpreted as life-threatening acts. Yes, it might fire the guy for even possessing a firearm but it would be extremely stupid in a public relations way. I, for one, would boycott the business if they did.
I posted a link to a story at #12 that had facts similar to what you are pointing out here and the shooter was not charged. (The shooter was a customer, not an employee, though.)
This Marine was the only person eating in a Subway shop and a robbery developed. He had his handgun the whole time, but he waited through the robbers taking the money, to see if they would leave without trying to hurt anyone. But then the robbers started herding the employees into the back and threatening them. That’s when he opened fire and killed one robber and wounded the other.
BTW, I remember seeing the grandmother of the killed robber on tv, sobbing that “he was such a good boy, why did that man kill him.”
My CCW instructor - a police chief - stated that if you’re ever asked to lie face down on the floor or are herded into another room, go for broke, armed or not - they’re statistically likely to kill you anyway.