Isn't that suggestion of ulterior motives a way of conditioning the interest of people by using a bogey man? "Oh, this guy is researching the relationship between race, genes and intelligence, I wonder if he likes to burn crosses...".
The obvious problem with this kind of pressures - that are very intense and widespread in the academic/political world - is the precedent they open. I find the analogy with the creationism/evolutionism debate quite apt. It's a form of obscurantism to use scaremongering, even if with the best intentions and for good political reasons, to obstruct the discovery of the truth.
Maybe we're better without knowing some things. I admit that. All the preliminary evidence that points to an existence of a relationship between ethnic groups, certain genes, big head sizes and psychometric tests results will eventually lead to some racist groups claiming a scientific support for their political thesis. I don't see the big deal. It doesn't make them right in any way. But in the end we can't really know what things we're better without knowing, because we don't know what we don't know and it will prove to be futile: the impetus to search the truth is too strong.
What if there are some guys with a couple of alleles selected and their common in some populations but not others (and, because of that, have some sort of cognitive advantage)? Dr. Lahn research has pretty much settled that there are differences in brain function between groups. Yeah, probably asians are smarter than whites and whites are smarter than blacks because of their different evolutionary process. But as you say the differences withing groups are much, much larger, and, in the end, the difference in genetics is microscopic when compared with the similitudes.
The danger is that, as it's already happening, genetics research when it comes to the brain is abandoned because of the fear of repercurssions if "politically incorrect" results are find:
This is grothesc because it has to do with pressure motivaded by political views and not sound scientif reasons. We know there are genetic differences between races that give advtanges or disavantges. Adult whites can digest milk much better than asians or blakcs. Some blacks have a gene that protects them from malaria that whites miss. Etc. etc. The brain is a potentially more dangerous territory, but that's not a good reason to not make science.
What has been happening to scientists like James Walton, Charles Murray, Arthur Jensen and many others is an absolute disgrace for a free and civilized society.