Seriously just stop giving this person a hard time. They voted for what is right, at least. Whether they identify outside of that party, who cares? It’s not going to change (and in any case worked in your favor toward) the election outcome, which is what you are actually upset about.
https://www.medievalists.net/2012/11/at-the-tip-of-a-sword-a-study-of-the-introduction-of-the-knight-into-anglo-saxon-england/