Wow. My stories have non-white characters all over the place, and nary a peep. And not secretly non-white characters, either, but people with surnames like Vang and Srisai, where you couldn't really say, "I'll bet that's German."

I hope you've found a better crit group, because, "white people should not put Asian characters in their stories," is not a critique I've ever heard from an actual Asian-American person. Ever. Eek.