I doubt my opinion is the 'correct' line but:

That there are speculative and probably marginal upsides to basing policies on this premise and there are concrete and known downsides to not do this (Jim Crow laws, Eugenics programs have been largely judged as abominations rather than successes).

Which is to say whether or not different populations have different (and I mean different as in different, not linearly better or worse) cognitive abilities may be true without being actionable or useful.