> Are Asians generally lacking in some relevant physical characteristic, such as height, agility, or reflex speed? 

Great question! To answer a question like that you might want to seek out some sort of researcher who studies diversity in humans, right? Somebody who looks at different populations and studies out how they differ in various ways? That's HBD. 

Because NBA membership criteria hasn't yet been politically weaponized the way other fields are it's possible to ask questions like those that just occurred to you - does this group tend to have characteristics well-suited to the task? Maybe not, in which case trying to cram more of them into the NBA would be a bad idea, right?

The most obvious characteristic here is height. The average American male is 5'9" but the average Asian American male is under 5'7". Since height follows something resembling a bell curve, when the NBA (correctly) selects way out on the right edge for very tall people, any group whose mean is more than 2" less than the norm is likely to underrepresent so we shouldn't be surprised to see Asian underrepresentation in the NBA.

Because we know that people differ in height and weight and agility and reflex speed and muscle mass and more, when we see some level of "underrepresentation" in sports we tend to figure there's probably genetic factors explaining a good fraction of it. Which suggests the possibility of doing research to see what those factor are. What we shouldn't do is automatically label the disparity - or research into it - "racist" and denounce it and institute policies to "address" it.

> you seem less interested in the scientific questions and much more interested in the policy questions

In the context of underrepresentation, the scientific question is "Do relevant differences exist that might help explain this disparity? If so, what are they?" The first question is boring because the answer is always "Yes" - different groups differ. Figuring out the precise nature and amount of differences tends to get researchers denounced as "racist" if they take it at all seriously, so precise estimates can be hard to find and harder to defend in public.

HBD gets demonized because once you accept that different groups are different in ways that can affect their interests and job performance, that has implications beyond sports. It implies that when you see some race "underrepresented" among, say, computer programmers or brain surgeons, this also might have to do with different groups being different. Which destroys the naive case for "addressing disparities". Without doing the work to figure out what the important factors are and how much they matter, we can't reasonably assume that forcing more people of type X into job Y is making those people better off...even if it "reduces disparities". Does that make sense?

I notice you have a table collecting and assessing possible harms from the practice but no similar table collecting and assessing possible benefits. In deciding whether to fight against some practice shouldn't we want to figure out the net effect - benefits minus costs - rather than just costs?

Given how widespread the social phenomenon is, surely there must be some benefits?

( Something something Chesterton's fence...)

Near as I can tell, the people who think it's terrible are in large part motivated by largely-false quasi-Mathusian claims related to "overpopulation". If we set those aside, younger brides tend to have more kids; all else being equal we should assume those kids have lots of extra QALYs (that wouldn't otherwise exist) and also presumably make their parents happy. Are those married as children happier adults on average than those not? How do we balance a claimed higher risk of physical abuse against, say, a lower risk of ending up childless or alone or financially insecure?

If your goal is to make the world a better place, just making the list available seems like the most Effective and Altruistic way of doing that, no? Software developers tend to be way too afraid somebody will "steal their ideas" as the best ideas are HARD to popularize. Nobody but you sees as much value in YOUR ideas as they do in their OWN ideas. In practice, good ideas are cheap; what matters most is following through with implementation (and being lucky and having good timing...)

Keeping your ideas secret might prevent other people from stealing them but also prevents other people from IMPROVING them. Or sometimes even HEARING ABOUT them.