What makes you think the way people are being grouped together due to being visually different are the same factors that dictate the largest differences in efficacy between people?

It's what the U.S. Department of Health and Human Services thought [1], and it's clear from the thread that the comment to which you responded was predicated on that.

There's no need to imply it's the GP's own opinion, and sotto voce that the GP is a racist.

[1] https://news.ycombinator.com/item?id=25408088

Those two things are not the same. Increasing the diversity of a study is not the same as thinking that the differences are so great between different ethnic groups and not so great between any other distinctions that it would make sense to test and roll out to them in isolation. No one implied anyone was racist, you might want to sotto voce reread the definition of that word.

I actually don't think that, I'm just pointing out there are options for those who do...