Sheegs, Sheegs, Sheegs.
First, racism and it's common bastardization.
Descrimination is a byproduct of racism, but not in and of itself racism. It is possible to have descrimination without racism, as is the case of the web site that is causing so much of an issue with you.
Racism is using a position of power by the ruling race to descriminate against a minority race. This is always the biggest argument when new students take a cultural awareness course in college and the teacher states that minority groups can not be racist. It's because people don't really understand what the word actually means.
As the ruling race in America is still whites, they are the only race that can actually be racist. Racism is defined by which group is in power.
Black only dating cites are, by definition descriminatory, but not racist.
J-Date is desctriminatory, but not racist.
Whites for whites WOULD be descriminatory AND racist as it is the race in power that is doing the descriminating.
Now, does this make it ethically right? that's a completely different question.