Would you correct a friend who is badmouthing someone?

Brian faced this situation.
He and his wife were having dinner with some friends of theirs.  The friends are Christians too, and generally very good people.  Brian enjoys being friends with them, and doesn't want to jeopardize that.

The friends started badmouthing some people in the neighborhood.  They were not only describing actions but moreso interpreting the motives behind those actions and besmirching characters.  It was uncharitable. 

Brian knew that God would not like this sort of gossip, and hesitated for a minute before saying something, because he didn't want his guest to dislike him. But he decided to say something anyway.  He said to his guests "Are you sure of the facts of this matter?  Would you like somebody speculating about you this way?  You might be right, but you might be wrong about them."  

Brian said that the male guest raised his eyebrows, and Brian interpreted that as meaning, "How dare you challenge me!?"   But despite that, the guests went on to other topics, and stayed just as long as they normally do, and still stayed friendly in weeks after that.  So no fallout.

Except that Brian noticed that the friends continued to engage in gossip after that, but just not in Brian's presence.  Was that a win?  Not in terms of getting the guests to rethink their actions.  So how was that a win?

Brian felt it was a win to him personally because he chose to be a representative of Jesus' message, even though it may have cost him friendship points.  He felt good that he was willing to take a personal hit in order to help promote the loving message of Jesus.