"The evidence conclusively shows" is not the way science works. I think your overview is well-reasoned, and ripe with good intentions, but that comment is what white supremacists use to justify their nonsense. Correlation is not causation, and a majority of the HN community understands this point (we keep revisiting it, so I'm making a weighted assumption.)
The more important question is why would it matter? Who cares if there are differences within or across racial groups with regards to intelligence? What reasonable social benefit is there in researching this? Intelligent people should seek ways to enrich the lives of others through their intellect, not find ways to build gates and limit possible outcomes.