If what skibidithink says is true, doesn't it mean that it's not a fallacy at all? And that the failure he identifies does undermine the entire thing?

Either way, seems like a very narrow distinction you are drawing when he is making the meatier claim that affirmative action is fundamentally flawed.

They are in fact committing the exact fallacy by focusing solely on competition for admission slots instead of how we comprehensively improve educational outcomes for underprivileged kids.

Admittedly, the article does a bad job framing that as the real goal while AA is a specific component. It makes it sound like AA in admissions is the goal itself.

There is a lot more work to do to prove that "investing in education for historically disadvantaged groups" doesn't improve society at large.