You really need to stop with the strawmanning. I'm not sure if you think it makes a convincing rhetorical tool or you just want to be snarky, but either way it makes everybody less inclined to take what you're saying seriously (regardless of the actual validity)
It's a narrative that keeps on popping up here.
"Oh Korean athletes just machines churned out." Which is incredibly insulting to Korean athletes. Then many of those people will talk about how "our" athletes are all small town kids balancing school and the prom and just out there doing it themselves, which is a complete distortion.
If it's not that, they must have cheated. Can't possibly be they had loads of talent and hours of hard work and the character to win. No, because they are Korean they are cheating machines.
His "argument" offered neither data nor evidence. Go point out all of his flaws.