I'm inclined to agree with you.
I certainly don't think that avoiding dangerous knowledge is a good group strategy, due to (at least) difficulties with enforcement and unintended side-effects of the sort you've described here.
The question of sex makes me fairly optimistic. Men and women are definitely distinct psychologically. And yet, as this fact has become more and more clear, I do not think sexual equality has declined. Probably the opposite - a softening of attitudes on all sides. So maybe people would actually come to grips with race IQ differences, assuming they exist.
While the scientific consensus has become more clear, I'm not sure that it's reflected in popular or even intellectual opinion. Note the continuing popularity of Judith Butler in non-science academic circles, for example. Or the media's general tendency to discuss sex differences entirely outside of any scientific context. This may not be the best example.
This may not be the best example.
Perhaps not for society at large, but what about empirically-based intellectuals themselves? Do you think knowledge of innate sex differences leads to more or less sexism among them? I think it leads to less, although my evidence is wholly anecdotal.
There is another problem with avoiding dangerous knowledge. Remember the dragon in the garage? In order to make excuses ahead of time for missing evidence, the dragon proponent needs to have an accurate representation of reality somewhere in their heart-of-hearts. This leads ...
A few examples (in approximately increasing order of controversy):
If you proceed anyway...