It's "wrong"? Laughable. How, exactly, is it "wrong"? It comes off to me as very plausible, and appropriate.

Lol.

This isn't rhetoric, this is lived experience. No character assassination required - the character in question has assassinated themselves

It's a valuable idea that everyone should keep in mind throughout their lives, and throughout their careers.

Same thing with people who speak negatively of others to you in private. Odds are they do the same thing, but about you, when speaking with others. If you confide something negative about someone else to them, they'll probably tell that person.