I've seen an online comment somewhere referring to this interview of him (it's in Czech, but has English captions). I don't have much interest in watching the full interview myself (though I probably should just to check what I'm talking about). According to this comment I had seen, he explains in this interview that he had that knee-jerk reaction to the pushback to recommending Bob Martin's "Clean Code" book in the public factorio devlog in part because of the political climate he grew up in (Czechoslovakia near the end of the Soviet Union, and then following it's dissolution) which was full of spurious accusations based on tangential links.

Myself, I distinctly remember reading the devblog post when it came out and thinking "oh boy, it's a shame he only learned about Clean Code today and clearly is unaware of Bob Martin's reputation on matters outside of strict software development". His comments in the reddit thread really just made things worse. I'm still hesitant to unequivocally label him as bad as many others, but simultaneously I don't hold much hope that he'll ever come out and publicly denounce his former comments.

Sounds like a relatively normal dude. It's foolish to care about "red-flag language", especially if you're also saying "he didn’t really say anything to terrible."

This really raises a lot of questions about Factorio's story and worldbuilding 😔