The current homogeneous politicization of science certainly isn't inevitable, as there are periods of rapid scientific progress in the past when this situation did not exist.
> People completely misrepresented Darwin.
I think that's overly intellectualizing things. Ethnic conflict and genocide probably don't have much to do with people's understanding of science, as there are still ethnic strifes around word, even though discussion of many genetic differences among populations is now generally frowned upon in academia. [1] And there has been ethnic conflicts everywhere since the dawn of time, since way before modern science, Darwin, or the contemporary history of eugenics.
> What cannot be published today?
Things like arguments made in "The Bell Curve" [2], or even "The Blank Slate" [3]? You can't really make those kinds of arguments without getting in trouble.
> I mean Journals like Mankind Quaterly still exist
I'd never heard of that journal before, but with an impact factor of 0.194 [4], it's probably safe to say that it has no influence whatsoever on science in general. (perhaps appropriately, as you say, I have no idea about the quality of papers it publishes) I'm sure many personal blogs are more influential.
But do you think you could conceivably publish a paper in Nature which cites something from that journal in a noncritical way? The barrier isn't due to low quality or the authors being ideologues, as there are papers cited in Nature with both of those defects.
[1]: E.g. https://noahcarl.substack.com/p/theyre-coming-for-behaviour-...
[2]: https://en.m.wikipedia.org/wiki/The_Bell_Curve
[3]: https://en.m.wikipedia.org/wiki/The_Blank_Slate
[4] https://academic-accelerator.com/Impact-of-Journal/Mankind-Q...