Nothing bizarre about it; Diverse viewpoints tend to strengthen a community, so considering it unfortunate that HN doesn't benefit from a broader demographic distribution is pretty defensible.
If you want to champion diversity of viewpoints, that’s a different matter entirely, and such conditions may be desirable, depending on the wants & needs of the group in question.
Take these things on a case-by-case basis. Don’t reach for top-down governance as a panacea when such a thing is neither requested nor required.
This is a non-sequitur; neither of those are communities in the sense under discussion.
I'll agree that there are some cases where a lack of diversity doesn't indicate any weakness in the community, but that is not the general case.
I don't know why you are bringing "intervention" into the discussion as I did not, nor did the OP. And who said anything about top-down governance? I noted only that the case for more diversity in HN is quite defensible, and it obviously is. NB I didn't claim it was correct, just defensible which is a pretty low bar.
So beyond "bizarre" being an overreach (ironically, verging on bizarre even before the ex post facto introduction of intervention, etc.), this is exactly the case-by-case you are asking for.
Do you think that e.g. a forum about child-rearing populated almost entirely by women exhibits “a lack of diversity”?
It's not ok to suggest that the Tech sector, being one of the most important industries for gaining financial independence and making an impact on the world, must remain the white male bastion that it is.
Maybe you’re really thinking about unnecessary gatekeeping or something? THAT is unfortunate.
But it’s vital to recognize the difference between these concepts. One is immoral, the other is not.