You dont even have to ask. Friend can just sit at the bar, or they can bring a second person and just be at a different table. If this is a trauma response, there are ways to make in nonintrusive. Plus, if the other person doesnt know you brought back up, theyre going to be more themselves, and youll see if theyre a sleeze or not sooner. Its not hard to pretend to not be a sleeze while youre being watched then turn it around immediately when youre not.