Kudos for keeping your cool NickB. Only thing I mighta done differently, since these guys were obviously looking for trouble from your account, is tell the restaurant/bar manager about it on my way out. If it's a place you like to go and have never seen these jerks there before, having 'em kicked out/cut off might keep 'em away in the future.

Had some troublemakers in the bar I worked at in Chicago a few times, and both instances I'm thinking about ended with them getting kicked out (ok yes, I helped with that part). Never saw 'em again and I was there for 3 years. Just my two pennies.