I see what you’re trying to say, but this is a fundamentally different situation like you said: This particular word is specifically used in situations where its use is important for distinguishing groups. There are no alternatives when distinguishing is necessary because the options aren’t just “transgender” and “not transgender”, there are also agender and nonbinary.
The alternative is to say the full qualifier of “People who are the gender they were assigned at birth” or “People who are neither trans nor agender nor non binary…” - At which point you’re just defining the word cisgender.
With JP it’s honestly more akin to saying “Ok so there are people who live in California, people with homes in multiple states, and people who don’t live in California. Californians, kinda-californians, and non-Californians.”
And then someone who does not live in California pipes up with “don’t call me a non-Californian because California isn’t real”.
If somebody lives in Zimbabwe, and they don’t like being referred to in terms of California or not California. While you’re vocabulary is consistent, when you’re speaking to this person from Zimbabwe it would be polite to not label them as a non-californian to their face.
This non-western, non-white, non-Christian, non-Californian theoretical person might get annoyed by being defined by all the things they are not. Even though every term is technically correct.
The analogy, like most, breaks down the moment we come back to the reality of the situation at hand:
1- The lines are incredibly close together. Nobody lives across the world, incredibly removed from gender. The English language itself uses gender heavily. 2- The person from Zimbabwe, in the metaphor, is going to Californian spaces and complaining that he doesn’t want to be called “non-Californian” because states aren’t real.
The context matters, and the contexts in which people use the term cisgender are almost always in direct contrast with one or more alternatives.
That said, I don’t condone harassing people, so I’m definitely against sending him messages unprompted calling him that… But he’s just in general against the concept of cisgender existing because it is predicated on the existence of alternatives, and he doesn’t believe alternatives exist.
To be clear in case I wasn’t before, I agree with you that “cis” is not a bad thing to call someone. I was disagreeing with the logic you supported the point with rather than the actual point itself. Peterson is 100% doing it because he’s a dickhead that wants to weaponise the language against trans people