You're just proving his point further. RINO is literally a pejorative designed to marginalize "moderate republicans". Pretty much nobody uses the term DINO. "Everyone knows" the term RINO because conservatives consistently bash anyone who doesn't embrace rigid conservative idealism. Pejorative nicknames are a common rhetorical tactic used by conservatives, "RINO", "SJW", "Feminazi" "Cuckservative"... liberals don't do this. Of course, you'll say that liberals will use terms like "racist", "fascist" "sexist", "bigot" but those are english words you can look up in the dictionary (and it is common for conservatives to use these terms as well when saying that 'liberals are the real bigots/fascists/racists/sexists!!'), whereas conservative pejorative nicknames are invented by provocateurs with the intent to humiliate their intellectual opponents.