It's racist, plain and simple. They are discriminating against a race from doing something by not allowing them to attend based on their skin color.
THAT IS THE DEFINITION OF RACISM.
This is just like skinny vs fat shaming. Its absolutely fine when an overweight person makes fun of a skinny person but god forbid it goes the other way, the world ends.
I'll repeat what I said before, this is disgusting.
That is not the definition of racism. That is the definition of racial discrimination. Question for you, why are you stuck to the word Racism when there is a better way to describe it?
There are many layers to what you said, but I want to first understand why people like you are so wed to describe it as racism instead of the more proper description "racial discrimination." Why are you so invested it in being Racism?