Idiot author aside, even if the students were outliers being sent to the Olympiad, that would not explain the consistent performance over decades. Relative to the size of the country, and compared to the other dominant nations, the outliers seem disproportionate.

According to https://en.wikipedia.org/wiki/List_of_countries_by_medal_cou..., there are smaller countries performing better (Hungary, Bulgaria, for instance) and similarly as well.