If an employee were to open fire in the store or its parking lot and hit a bystander, Pizza Hut would be on the hook for a lot of cash.
Also, that radio host is an epic douche. "He had the gun at my head, and then I just lashed out." "Good for you!" The poor guy is still visably shaken from what happened, and this turdball congratulates him not for using the gun to defend himself, but for lashing out when a gun is pointed in his face. If the robber pulls the trigger before he gets to his gun, the driver is dead and this host doesn't give a shit so long as the robber wasn't an immigrant or on welfare. In fact, I'm guessing he doesn't report the story at all because it would back up the argument that carrying doesn't do much good when you're surprised by an attacker.
You can consider this guy a hero if you want, but I consider him epically stupid, guns or no guns. Fighting with a robber who is attempting to flee and holding a gun in your face is a very good way to get real cold real fast.