I'd have tapped him on the shoulder and said "erm, sorry, who are you?", then whatever he replied say something like "Sorry, never heard of you" or casual deflect whatever trumpt up thing he said, then (as suggested) held out my hand to the girl and said "the bar is way too crowded, let's go over here", and just lead her away.

As Phil says, women loves confidence and a protector. If you can show you can stand your ground around a larger physical specimen then that's an attractive quality