I'd keep out of it.
As advised, the notion of leaving a teenage girl alone with a man neither she or her mother know is not clever, but itr is their business, rather than yours.
You can use it s a lead-in to a conversation with your daughter about responsible behaviour in general, and responsible sex in particular, but steer clear of the "You don't want to do like .... did do you ..." line of conversation. Dissing your daughter's friends is not the way to show you are on her side, and she may well tell her friend what you said, and that way likes complcations.
Nice and simple is the rule with teenagers - guidance not lecturing, rules for health and safety, not because you are a killjoy. Take that approach, it works better - i know.