I assume you are talking about so-called Black Universities?
"Despite being founded to serve Black students who were systematically denied access to higher education, HBCUs have never legally prohibited enrollment based on race. Today, some HBCUs have a significant percentage of non-Black students, with a few even having majority-white student bodies."
Still, Private Universities can basically do whatever they want. Plenty of Private Christian Universities. Sheeet, even Kanye got one. Who the hell knows what they doing in there...
You need help explaining the difference between public and private?