At the risk of perpetuating the disagreement, IMO if anything is similar to the creationinst debaters, it's the voices against the memo.
Going through the few recent HN discussions on the topic, I found that on the one side, you had people (including an actual scientist in the domain) telling that the memo basically got the science (even if not ultimate conclusions) right, as supported by _even more_ research people linked to, vs. the other side saying he presents "outdated" views of "biological determinism", etc., with no counter to the research cited by the memo itself (not to mention others) - just unsubstantiated accusations and dismissals.
Instead it wanted to connect that research to a) company policy and b) American-specific political divides. And to do that required a battery of assumptions regarding intention, merit, aptitude, worth, values.
That's where the wheels came off and everyone started projecting their own ideological interpretations, and you've been arguing past each other ever since.
Everyone agrees it was polite, but well-argued and coherent is where not everyone does agree.
I've seen people with advanced degrees host debates where they legitimately advocated creationism as the truth against evolutionary biologists with equally advanced degrees. They were polite, and their supporters would say well-argued and coherent. But anyone who knows anything about the topic would see that the creationists weren't actually adding to the discussion or making strong points at all. Those creationist debates are always unsatisfying and exhausting to listen to, and after a while, that schtick becomes old and non-creationists stop engaging because it's just boring. But creationists will attend and be excited every time because having a debate against a real scientist legitimizes them.
That's how this memo thing felt. Nothing new was added to the discussion (at least not to those of us who have had this discussion before) and it just seemed like an opportunity that some less savory folks jumped on to promote some out-dated views (and more importantly, for mainstream media to jump on to paint all of tech as a place where those views are the norm. That story sells despite how wrong it is).
FWIW, I do hate impoliteness though. I understand why people felt defensive for the author after watching the internet freak the hell out (in rude or dismissive ways) about the memo which was not impolite in itself.