I'll point out that a major component of why universities seek "diversity" is not because of an expected value in a broad assortment of perspectives, but to ensure that parts of the population aren't locked out of the academic system in a self perpetuating cycle. Affirmative action supporters generally look forward to a day when the groups favored by affirmative action policies will be able to break the cycle and compete evenly with other applicants purely on the basis of qualifications. The policies are more for the sake of the minorities, who the universities have nothing against and would like to see able to compete on even footing, than for the universities themselves. It doesn't follow that this sort of favorable treatment should extend to a diversity of ideas that the universities actually do have something against.
They could compete evenly now, if by evenly we mean objective standards for winning the competition.
It seems that "compete evenly" means instead "win just as often", and the rules of the game will include deliberate biases until that occurs. In fact, it will include such biases even when they win more often, as is the case with women in higher education.
Related: Heuristics for Evaluating the Soundness of the Academic Mainstream, Admitting to Bias, The Ideological Turing Test