I can look at someone, and they generally "look Slavic" (in appearance and culture) or "look Germanic". Of course, the boundaries for any given group are not strong and they tend to blend into one another (much of Central Asia is blender central, for one), but that's not to say there isn't some core, end-of-spectrum point of Slav or Chinese that has a strong bearing on the people around them.
Is that not how most migration theories go? Austronesian, Indo-Aryan, Germanic, etc? A core home territory with a clearly distinct genetic and cultural makeup spreads out and heavily alters, blends with, and displaces local populations in far wider areas? Obviously, a far-flung Polynesian isn't going to be quite the same as a Filipino in genetics or appearance, but we have no problem understanding that these two groups are clearly connected genetically, culturally, and historically, in ways that they are not connected to, say, an Italian.
Ultimately, people are defining a race as a distinct collection of different genetic/phenotypic gradients, and where there's a strong overlap of X,Y,Z,J,N haplogroups/etc we can consider that a race, and we of course consider border areas (eg Poland) to be mixtures (Germanic/Slavic), and we have racial hierarchies (like Caucasian ->European ->Germanic ->Saxon ->Bobstonian) that reflect the various levels of specificity and implicitly accept there's unclear borders at any given level.
I would say this is making an extreme contrarian statement (in that it is taking a very extreme position of total negation). It seems more a cultural-political statement than anything else.
And while I don't believe there's much evaluative difference between races at the genetic level generally, this statement:
Any attempt to use genetics to rank populations demonstrates a fundamental misunderstanding of genetics.
I don't see how it can live in the same scientific framework as Darwin. There will always be some level of survival and breeding inequality between population groups. Humans don't have some divine opt-out from natural selection, even if what they think makes one group superior to another has little to do with what nature thinks.
There is a clear, and stated, agenda here, and while I concur that it is necessary (suppress racial supremacy), they've taken it too far.