Putting aside the "good for the goose, good for the gander" test (if there were a whites-only roommates push, I'd be joining protesters down at Crouse-Hinds), I don't think SU wants to be in the business of limiting kids' exposure to diversity in that way.
We're told (and I tend to agree) that part of college is learning about other cultures and generally getting educated in diversity. Self-selecting roommates based on some similarities (say, former high school classmates) is, in my opinion, suboptimal. Doing so on the basis of race - that is, enabling students in a university-mandated process to discriminate on the basis of race - is even more inappropriate and legally questionable.