Very true. I think most HBD proponents are somewhat overconfident of their conclusions (though most of them seem more likely than not). But what I think he was getting at is that we would have great difficulty acknowledging if it was so and that any scientist that wanted to study this is in a very rough spot. Unlike say promotion of the concept of human caused climate change which has the support of at least the educated classes, it may be impossible for our society to assimilate such information. It seems more likely that they would rather discredit genetics as a whole or perhaps psychometry or claim the scientists are faking this information because of nefarious motives. This suggest there exists a set of scientific knowledge that our society is unwilling or incapable of assimilating and using in a manner one would expect from a sane civilization. We don't know what we don't know, we do know we simply refuse to know some things. How strong might our refusal be for some elements of the set? What if we end up killing our civilization because of such a failure? Or just waste lives?