No, that is not the justification being used.
The argument used to justify this racism is that a rich education requires exposure to diverse people and ideas, and so the educational mission of the school requires that they bring in sufficient numbers of otherwise-underrepresented racial groups. If they can't do this, they say, they won't be able to give their students a good education.
[Note that I'm just playing devil's advocate by citing their view; I actually think it's bollocks. Sure, being surrounded by diverse ideas is important in education. But if they were truly interested in this, then they'd be trying to recruit based on that actual argument, by looking for Protestants and Catholics and Mormons; tall and short people; introverts and extroverts; right-handers and left-handers; city folk and country folk. The fact that the only dimension along which they measure diversity is race reveals that the justification they give is nothing but a convenient rationalization.]