Also, I don't just mean they are reactionary in certain area or in their personal life (Like Aristotle was important for biology despite being an apologies for slavery)?
I mean worth looking into their thinking precisely in areas where they're reactionary.
Possible suggestions (not saying they're justified) that I expect people would put forward include:
- Carl Scmitt
- Heidegger
Yes, he uses simplistic analyses from a position of ignorance when it comes to LGBTQ folks, analyses that, to me, reveal a dogmatism for a particularly reactionary branch of Soviet Marxism. And that reflects poorly on his other work.