Sorry I didn't see this response earlier.

Yes, extremism to me does feel orthogonal to political orientation. "Delusional centrist" is closer to what I had in mind.

Here's the thing that I think is important: you can't talk to extremists rationally. Their mental world model doesn't match reality in big chunks, so there's no shared world view to agree on.

Perhaps I am redefining "extremist" but that's just my mental model.