Dawkins is trending because of the typical Twitter outrage cycle. The text of his tweet is not important, it's the subtext, the meaning that readers insist on reading into it.
Hitler was kind to animals and a vegetarian. Yet, we can't say this because despite being true, the subtext is outrageous, with people insisting that somehow you support Hitler.
Things like "eugenics" is all around us, but we aren't allowed to use the e-word to describe. Couples practice it when they go to sperm banks and choose donors with the characteristics they like. Other couples use prenatal genetic screening.
Gene editing is available. I'm curious which will be the first lawsuit: the child who sues their parents for editing their genes against their will, or the child who sues their parents for failing to edit their genes that would've fixed a defect.
Scientifically, selective breeding of humans would work. We all agree with this when laughing along with movies like "Idiocracy". We all disagree when selective breeding is called "eugencis", because subtext, only monsters agree with eugenics.
I mean, the visceral reaction against eugenics is totally justified. Any government involvement here would be evil, and not just the Nazis pursuing racial purity.
But it works both ways. Let's say we discover a gene we can CRISPR into unborn babies that'll boost their IQ by an average of 10 points, should governments ban it? If you say "yes" then you agree with the principle of government run eugenics, just disagree on the application.
BTW, dictionary definitions of the e-word can be funny, such as this one, implying eugenics was a fine thing before its perversion by the Nazis. 
