I heard on the news story (I listen to 1080am and 820am all day) that they DID rob the customers for their wallets. I know I didn't hear this wrong, but maybe they got the story wrong. Or this was another incident. The one I heard about was on I-35 in Fort Worth.
This is a tough one. I always wonder what I'd do if someone came in to rob the joint, or just start shooting as in Luby's a while back. In the second case, there is no question. The guy is there to kill and that's it. That's a life or death situation. In your friend's case it makes sense to me why he didn't try to gun them down inside the restaurant (even though I wish he had been able to). It's also a good thing he was there if things escalated. At least there was someone in the building with experience and a firearm.
This does bring up some questions to me. For one, remember the discussion about off duty cops open carrying? I wonder how the situation would have been different if a BG spotted a gun on a guy's hip. In this situation it would seem better to have a concealed weapon so that you could get the drop on them if they let down their guard. Now if it was five or six LEOs open carrying...that could turn the tables.
Another issue is the lack of firepower. You know how much I love my .22's and such, but seriously in this situation it would be practically useless other than a last ditch effort if things went really bad.
This makes it all too clear that you should have formidable firepower available, extra mags and lots of practice. Another discussion about whether to keep the gun cocked and locked or not brings up the point that in a situation like this, you might as well not have a gun if it's not already chambered. That "click click" sound would be enough to give you away.
As far as Waffle House goes. They all seem to have the same layout. You can pretty much see what's going on in the entire place. Maybe that's why these guys are targeting that establishment. I heard that the police suspect that these are the same guys that have robbed at least one other one.