I'm really sorry that happened to your friend. That jerk is just feeding the anti-gun fire. I'm not sure what the legal aspect of this is, but here's how I look at it personally. The instant he put his hand on the weapon, IMO, that's a threat. And I know how I react in those situations, and it's not very nice. Physical force would have come next, no questions asked.
I'm not saying your friend did the wrong thing at all. She walked out of there without any bullet holes, so she did the right thing for that situation. The only thing I would advise is if something like that ever happens again, walk away and as soon as you get outside the door call the cops.
Behavior like that has no excuse and it's people like that who give us all a bad name. That guy is going to pull that on the wrong person one day and he's probably not gonna live through it.
A hit with a .45 ACP beats a hit with a .22 LR everytime. A hit with a .22 LR beats a miss with a .50 BMG everytime.