I was just like "you seem to be telling the dude that he isn't using tankie correctly, but that's not how language works"

What I actually did was provide some context for the term and how it's used nowadays. The point of the history lesson was to point out how the term became appropriated and set the stage for laughing about how some Trots get called tankie nowadays. The point of "how it's used nowadays" was go provide a counter-narrative for the "definition" they were taking their own liberties with. I did what they did, but I'm more correct in my context.

Injecting a prescription vs description debate isn't really relevant.

And then you replied that I'm wrong, and seemed to be making an appeal that the negative connotations had to do with the invalidity of the definition.

Yes that was me misunderstanding which word we were talkjng about. There's another thread I had in mind. I don't think what I said there applies to the word tankie.

Our wires are so crossed at this point that a random car in 1960 Spain just got spontaneously hotwired.

I can make it worse, just give me time.