I don't think pillefitz is asking if the author's racist arguments in general are sound. I think he was asking if the arguments in this particular article are sound.

Many racists are actually quite competent outside of when they are trying to argue for racism, and this particular article doesn't seem to be making a racist argument.

It does talk about the possibility of an over performing ethnic group, and suggests Jews as a candidate, but that's not inherently a racist argument. There are in fact ethnic groups in many countries that do over or under perform as a whole, but this is almost always due to cultural factors.

In particular ethnic groups where education and scholarship are a big part of their culture unsurprising tend to over perform in general society unless their culture also is big on minimizing interacting outside their group.

Jewish culture is such a culture and they have long been over represented in intellectual fields unless they are in a country that has high social or legal barriers to keep Jews out of those fields. Heck, this is probably why so many stupid conspiracy theories have them as the people secretly running the world.

It's similar with many Asian cultures nowadays. Just take a stroll through the campus of Caltech or MIT if you want to see that those groups over perform. At both those schools around 48% of undergraduates are Asian. That's way above the 7% of Asians in the general US population. Even if we take into account that Caltech has a disproportionate number of students from California (if you can get into a top STEM school and are from California, are you really want to go deal with Boston weather?) and California has a high Asian population (about 16%) the 48% at Caltech is way higher.

That said, I don't think the arguments in this article are really all that good. He is emphasizing the IMO since 2020 and talking about how 2022-2024 stand out. But when you look farther back instead of starting at 2020 then 2022-2024 are still good years, but not really remarkable years for Romania. Over the period it has been good it has had some major changes in their education system which I think limits what you can infer from recent IMO success. I've got another comment that goes into more detail: https://news.ycombinator.com/item?id=45071972