The woman is still in the class, so obviously affirmative action hasn't affected her. However it is a fact that Stanford uses affirmative action (see https://alumni.stanford.edu/get/page/magazine/article/?artic... for example). I think jquery was pointing out that this affirmative action might explain the reduction in diversity after the "weeding out", which the article author mentions. It's nothing to do with racism or assuming that black people are stupid.