There are several chapters at Southern with black women, as well as other women of color. It is not a big deal. DPhiE had issues that made PNMs not want them (not including members' races).
And if you look at their past recruitments, there were not unlimited women who wanted them. There weren't many women at all. I think most of their members came from COB.
When you market yourself as the un-sorority, you will turn off a lot of Southerners.