I've heard this objection before and I often wonder if the people making this argument secretly think that some races really are inferior, but that we mustn't talk about it.

Or, perhaps you are implying that such research might overturn our egalitarian, meritocratic society. Personally I have no fear about that. It's obvious that some people are born superstars in pure physical ability, and yet we all still enjoy sports and not all physical work has been dominated by one race.

And I think you can see that there would be huge benefits in learning what the non-genetic factors of intelligence are.