[mikeash]

I find it ironic hat the author is dividing all of humanity into two tribes (A and B) and then stating that they cannot coexist.

[tines]

The philosopher Karl Popper wrote about this and called it the Paradox of Tolerance: https://en.wikipedia.org/wiki/Paradox_of_tolerance

[nickbauman]

Except that A by definition has a mandate of non-coexistence.

[mikeash]

I'm sure plenty of "it's us or them" people justify it on the basis that the other group thinks "it's us or them."

In any case, I'm not criticizing the author. This sort of thing is a fundamental paradox of tolerance. It's hard to tolerate those who would not tolerate you.