Trigger warning: racism.
I personally found this letter incredibly difficult to read. Beyond the content of the email, the apology is also terribly written, and reads like Nick, an intellectual leader in EA and longtermism, might still hold these views today to some degree. It also reads like Nick is primarily just trying to do damage control for using a racial slur, or preemptive PR work for some other reason, as opposed to focusing on the harms he may be contributing to, and the folks he is apologizing to. In this context, this also sounds like a dog-whistle:
Are there any genetic contributors to differences between groups in cognitive abilities? It is not my area of expertise, and I don’t have any particular interest in the question. I would leave to others, who have more relevant knowledge, to debate whether or not in addition to environmental factors, epigenetic or genetic factors play any role.
Myself and other EAs I know are worried about professional reputational risks of continued association with the EA movement or longtermism. This is not just a PR risk, and despite my view that this reflects terribly on Nick and any comms experts who may have been involved in this, I don't want this to imply that the PR angle is what we should be primarily concerned about here-it isn't! But whether or not one of the leaders of EA has held racist views for decades, and whether he still basically holds them today is important.
It has real implications for the movement's future, including selection effects on people who may become more uncertain about the views that intellectual leaders of the EA/longtermism movement hold (and by extension, its intellectual foundations), whether EA is a community for "people like them", and whether EA is a movement that is well-equipped to preserve a future for all of humanity. Even if they aren't uncertain, they may be more reluctant to take risks to continue or become more outwardly involved in an increasingly controversial social movement. This may also affect the view of current and prospective donors to EA causes.
These are not concerns held solely by "EA outsiders" or those who are already unsympathetic to EA.
Reactions on Twitter-read on at your own peril!
(The EA forum seems to default to strong-upvotes on your own posts. I don't know why this is, but I'll probably change mine to a normal upvote if this post gets some engagement.)
There are, however, opinions on this matter which go in a very different direction than the pieces you have cited. For example, the various studies referenced in this thread of threads.
For instance, the author mentions researchers saying there is no evidence for the narrowing of the substantial 15-point IQ gap for people born after the 1960s, and that there was no gap-narrowing for other education-related tests (SAT, ACT, GRE) for the last three decades. (He also mantions similar finding about consistently higher IQ scores for northeast Asians compared to whites.) Or that in a survey more than 60% of intelligence researchers estimated that genetic differences account for half or more of the gap. He also cites evidence on twin and adoption studies supporting the large heritability of IQ. Adoption studies also support black-white-East Asian score-gaps. Additionally, admixture studies found that black-white mixed-race populations have, on average, IQs between the averages of white and black populations. There is also various other data supporting the heritability of the gap. Moreover, he references various studies and experts who point out that the Flynn effect is not evidence against IQ gaps being largely heritable, even if the Flynn effect itself is mainly caused by non-heritable factors. The reason is that the Flynn effect was not accompanied by a narrowing of those gaps.
To go back to the original topic: From the above and your referenced posts it is apparent that there are substantial disagreements between intelligence researchers in these matters. Non-experts should not be chastised for regarding this as an open empirical question. Nor is it acceptable that only defending one side of the debate is allowed, at pain of risking severe social repercussions.