@Juli-and-Brian0, you are obviously very kind and thoughtful people to worry about the bad effect a poor review would have on the booking travelor.
It is too bad the booking travelor did not have the same regard for you when they brought along their boorish friend.
The person who books a listing is responsible for the behavior of the people they bring.
If the person who books the listing brings along people who cause trouble, then the person who books the listing is not the kind of person you want to stay with you.
It is completely fair.
If they want to protest their bad review, they can post a response. Hopefully in that response they can promise the next host that they won't bring along their goofy friend.