Sure. You could argue that judging someone on the basis of extracurriculars is discrimination in favor of people with wealthy parents.
But, there is no current law, on the books, that explicitly says that discrimination in favor of wealthy people is illegal.
Instead, the law prevents discrimination "on the ground of race, color, or national origin".
And furthermore, I do not believe that that there has been significant court ruling saying that discrimination in favor of wealthy people, would be equivalent to discrimination on the grounds of "Race, color, or nation origin", if you are going to make that argument.
You're correct that this is essentially the argument I'm proposing (although you could broaden 'wealth' to a wider range of racially influenced factors of educational success/access). It might not have been made before - Yale may try to make it.
> All persons who apply for admission to colleges and universities should expect and know that they will be judged by their character, talents, and achievements and not the color of their skin.
If I achieve better grades and have broader extracurriculars versus somebody who was in a substantially less advantaged position than me, how much of that comes down to my 'talent' and 'character', and how much comes down to my wealthy parents?
Yale could attempt to make an argument that a proper comparison of character, talent and achievement across a diverse, heterogenous population requires interpreting these elements in their context (the bar should be higher for those with more opportunity). Then they just need to establish that their equity programs are well substantiated by educational barriers which are inescapably racialized.
Basically the argument is that since race in America is unavoidably intertwined with educational opportunity, it is not possible to have an admissions procedure which is 'neutral' with respect to race; that in fact equity programs aim to strike the best balance in this conundrum, and are therefore the least discriminatory policy available in the overall context of the program.