There is at least one site where questions based on racist ideas are generally accepted, and that is Skeptics. We also get anti-semitic, misogynistic or xenophobic claims in questions there, they're all on-topic. Disallowing those would just mean that you can't ask Skeptics to debunk those claims. We don't endorse them, even if we quote offensive claims in questions on our site.
There is one previous case where this issue was discussed. I removed the question myself back then with the following reasoning:
I'm going to close the question, editing it into shape is not an
option as the author disagrees with the fundamental premise that the
question needs to be framed differently. I also can't really let the
community close it in this case as the bounty prevents any close votes
anyway. But my impression here is that a majority considers the
question problematic. The question also received a lot of flags.
Now, I actually see two different issues with the question. The first
issues has been discussed here, race is widely considered as not a
useful criterium in genetics and the way it is used in this question
is considered offensive by some.
The issue here is not political correctness, but correct biology and
professionalism. In this case the terminology can reflect negatively
on our site as a whole.
Another issue I have with the question is that it contains no
motivation for asking the question at all. Just asking "Is there a
difference in X between Y groups" without any indication why you
suspect there is one is not a good question in my opinion. I don't see
how this question can further any understanding of biology or how it
could be useful.
This decision is not necessarily final, as we don't have any
well-developed policies on this matter. But I also don't want to leave
this question open and bounties, immune from closure by the community.
If I applied my old reasoning today, I would very likely close the question that triggered your post. I did actually see that question earlier today and considered closing it, but decided to see what the community does with it. We don't have a firmly established policy yet, and there are certainly a few fuzzy borders with questions about races on a site about biology.