Im sorry but not wanting to have sex with another race does not make someone racist.
I guess it would depend on their reasons for saying so. I'll just say that in my experience people who would make a distinction are doing so because they have racist feelings about it. I've never heard anyone say, "I find that race of people disgusting," who didn't turn out to be racist in some way. You have to remember that in doing so, you are painting with an incredibly broad brush.
do you understand the difference between physical repulsion and racism? I would not sleep with an ugly fat girl, but I don't have some inherent bias against them as people.
But most people do have an inherent bias against fat people.