By the end of the article, you realize that the whole point is about the negatives of "culturalism". He says:
> Like racism, culturalism distracts away from asking more meaningful questions, and obscures pertinent facts.
> Like racism, culturalism puts a large group of people beyond rational understanding.
> like racism, culturalism destroys individual agency.
> Culturalism causes real harm. It obfuscates the truth.
But he hasn't backed this up at all, except for a single lengthy anecdote about Gladwell's chapter. Speaking as someone who has lived in in several different countries besides the US (including 8 years in one), cultural attitudes are extremely important everywhere you go and can explain lots of important things.
Just look at Geert Hofstede's "Cultures and Organizations" if you want empirical data for it.
Seeking cultural explanations for things is no different from seeking any other kind of explanation. Even if it winds up not being true, it's perfectly valid to wonder if cultural things are at work. Looking for cultural explanations is not a distraction, and it does not put anyone "beyond rational understanding" -- to the contrary, it tries to explain things rationally.
I understand that the author is bothered by speculation about Korean culture, but honestly, that's just silly. It's not emblematic of some kind of anti-Korean attitudes in US media or anything, and the author's done nothing to show that it is.