OK? A few minor nitpicks to start with.
We know something about the early Hellenes from the Iliad. It was first written down in the late eighth century BC, at the end of the Greek Dark Age, after the Phoenicians taught the Greeks how to write again. It recounts events some four to five hundred years earlier. Although we think of the poem as being about the Greeks, Homer’s warrior heroes belong to the Achaean nobility, which suggests that it was the Achaeans who overthrew Mycenaean civilization, not the Dorians, who would descend upon Greece and displace the Achaeans a hundred years later. Archeology confirms this supposition, for Troy was burned around 1200 BC, and the traditional date for the Trojan War is 1184 BC. The Dorian invasion is dated by various ancient historians at 1149, 1100, or 1049 BC.He's either never read the Iliad, or doesn't understand it, and he understands little if anything of the scientology and historiagraphy of the Trojan War. Menelaus and Agamemnon were kings of the Mycenaean civilization; saying that they overthrew it as part of broader picture that saw the sacking of Troy as merely one event in the greater Bronze Age Collapse makes no sense. Either the Achaeans were an important element of the Mycenaean palace civilization of "Ahhiyawa" already, which makes sense given that it's supposedly a Hittite transliteration of the word that comes to us as Achaea, or you can't take the classical narrative of successive waves of Achaean and then Dorian invasions too literally.
But this is a minor nitpick that doesn't much impact the general thrust of his argument really.
The second nitpick, which is also minor, is that he repeatedly calls the Romans and Greeks "northern Europeans." This is obviously false, since they are attested in southern Europe; Rome and Greece, respectively, although both tended to get around in the Mediterranean region and beyond from time to time. What he means to say, of course, is that they are of a physical type which is today associated with northern Europe rather than with southern Europe. There is no convincing model by which the Greeks and Romans are literally from northern Europe—the best model is the so-called Kurgan Theory or its proposed update, the Revised Steppe Theory, which has Indo-European languages and culture spreading from the Pontic-Caspian steppes, mostly during the early Bronze Age, and certainly before writing came to Europe. Most likely languages ancestral to proto-Greek and proto-Italic were already forming in the Balkans, although models that get us from putative late Proto-Indo-European cultures such as Cucuteni-Triploye to the historically attested Greeks and Romans is a bit hazy, the general story that derives them from the steppe is strong; and it does not derive them from the steppe via northern Europe.
Why those physical types are under-represented in the region today is, of course, the big question. There are obviously lots of different migration models. Some proposed for Indo-European expansion include a cultural and linguistic dispersion that had little genetic basis behind it at one extreme. The other extreme is a nearly complete population replacement—which most archeologists decry as too radical, despite the fact that we have at least three historical models that I can think of off the top of my head for exactly this happening: modern day North America, Australia and New Zealand.
A slightly more nuanced model which is the one that fits best with the scenario described in the article is rather the installation of an invader force which conquered and installed itself as a cultural elite over a larger population of authochthonous natives, but who managed first to impose its civilization, language and material culture to at least some degree on the conquered nation. A good modern example of this would be Mexico, where Spanish conquistadores claimed the nation and imposed Spanish culture and the Spanish language on a large population of natives. Although they were successful, naturally, in doing so, the basic physical features of the Mexican nation owe much more to the Aztec and other native populations than they do to the Spanish even today—even though the cultural and administrative elite and upper class is still demonstrably and observably more physically European than the masses. Even today, many centuries after the fact.
This is probably the model by which the Greeks and Romans transformed Greece and Rome into the nations we know them today, and yet which turn up repeatedly in ancient texts and art as observably more like the northern European than the present day southern European—because the cultural and administrative elite still got that way as invading conquerors rather than as natives. Only after many, many generations did the invaders eventually get more or less genetically swamped.
UPDATE: Although what I wrote back then is still completely accurate with regards to the Greeks and Romans, in particular, archaeogenetic studies (i.e., DNA sampling from skeletons found at archaeological dig sites) suggests very strongly that there was actually considerable population replacement and folk movement going on. The Corded Ware cultural horizon (admittedly, more northern European) shows that 75% of the DNA comes from the steppes—the Yamna horizon which is the Proto-Indo-European homeland. What this means is that the northern European "stock" is the Indo-European stock to a great degree after all, and it comes from the steppes of Eastern Europe originally.
This means of course, that the Greeks and Romans—or at least the original people who brought the languages that later evolved into Greek and Latin—were also, as the article suggests, built and colored like northern Europeans. Because the substrate population density in southern Europe was greater than in northern Europe, the steppe physical type remained in northern Europe (which, honestly, probably had a similar physical type already. Look at the non-Indo-European Finns and Lapplanders relative to the Indo-European Swedes and Norwegians, for example.) In southern Europe, it was eventually swamped. But it probably took many generations for this to happen. Today, many centuries after the Spanish conquest of Nueva España from a variety of Aztec, Toltec, Inca and other empires, the elite classes of Latin America are very visibly and notably different than the lower classes. The former is very Spanish and European in physical type while the latter is very indio. In India, the physical distinction between the Brahmins and the lower castes seems to preserve an ethnic distinction described in the Rigveda between aryas and dasyas that has persisted for millennia. The Rigveda's timing is a bit uncertain but most likely it was written before the fall of Troy.
I haven't read that any archeaogenetic studies have tried to track the spread of steppe elements (i.e. Indo-European languages) into the Balkans or elsewhere in southern Europe, though. No Baden culture archeogenetics studies that I know of—although I'd be real interested to see one done.