The rationalist impulse is to construct a story as a puzzle with a solution that neatly resolves it and can ideally be found ahead of time if you're clever enough.
Horror writing on the other hand keeps you in the dark. You know that things are bad but you don't know how. There's a lot of uncertainty and it doesn't all go away.
Nick Land writes horror. Nostalgebraist wrote a sort-of-horror story. Neither is a central example of a rationalist, and a lot of rationalists hated the ending of Nostalgebraist's story for being unclear. This is not a coincidence.
Unlike >>/6656/, when Lovecraft wrote stories about the horrors of race-mixing he didn't pretend to have it all figured out.