It’s a combination of those things.
Because rationalism the coherent phenomenon was founded with the more or less explicit intention of building a cult, Yudkowsky’s original rule-set incorporated all of the basic cult rules, which every cult leader tends to be able to work out mostly for themselves by looking at what they outwardly want to build (a movement) and what they inwardly want to do with it (retain personal power over that movement)
So, for example, the particular way that Yudkowsky frames “objectivity” coalesces later on around the “object level” vs “meta level” dichotomy, “low” vs “high” “decoupling”, the “grey tribe”, but it’s there from the beginning in his insistence on the highly specific and idiosyncratic framework proposed in The Sequences, his constant explicit insistence on the rarity of his chosen elect, and also just in (a) his consistent lambasting of people who work outside that framework in the text of The Sequences themselves, and (b) his sometimes hilarious neg/love-bombing of the reader
Of (b), my favourite example is that passage where he bizarrely takes an unnecessary moment to call you an idiot if you think that there’s a universal clock measuring time throughout the universe, in the full knowledge that his nerdy readers are aware of relativity
So the whole system, beginning with LessWrong’s very founding, is geared to control the framing in ways like not naming names. Naming names is a failure of objectivity, because it brings in the sorts of particulars that might exercise your ordinary human judgement - ordinary human judgement is bad, we know this from Daniel Kahneman, and that’s another rule of objectivity. So, moreover, the whole system is geared so as to keep “objective” framings which favour HBD “in-group”, and to displace good human judgements (‘Richard Hanania is a ridiculous mendacious racist’) into the “out-group”).
HBD hegemony within the movement (in influence if not in numbers), moreover, could not but have been the eventual outcome of the same rule-set. In spite of his own protestations, Yudkowsky’s pugilistic naturalism was sufficiently both insisted upon and theoretically naive as to ultimately yield hegemony to the HBDers by sheer inertia: once you have eliminated and salted the earth of any thinking which fails to embrace the most childish physical-scientistic reductionism, then when your rules for thinking enter the arena of politics (especially American politics) and human biology, you have already ceded all possible theoretical ground to HBD, and any counter-weight you try to introduce thereto becomes the pathetic mewling of Kahnemanian irrational beliefs. Your rhetoric already implied “it’s just basic biology” from the very beginning.
So, for anyone keeping score, the only way for anyone on LessWrong to win the rhetorical argument is, unfortunately, just to be normal, and violate one or more of the LessWrong standards for thinking.