1st amendment, the right of people to peaceably to assemble.
Granted, you may not like racists have the rights of the constitution, but they do, now why this kids chose to "peacefully assemble" with only there own kind, is there business, but simply put, they chose to, they wanted to, I guess they thought they were actually african american and that this was okay.
What I said was that it's dishonest to pretend it isn't segregationist and racist when it's designed specifically to separate the whites and blacks of an otherwise combined group.