Before this, I read your post as saying mainly, 'You should believe true claims instead of false ones,' without any non-commercial way of distinguishing truth from falsehood. Likewise, I saw no guidelines for how to choose "functional" belief systems.

If I read the summary charitably, it seems to mean that 'When people pride themselves on their rationality due to their atheism, this tends to get in the way of optimizing for truth and/or functionality.' This is technically progress. But I get the impression the LW community already hates people patting themselves on the back for atheism, and may actually discourage it too strongly.