That's racism? Heck, we were doing that in high school. I'll never forget when a substitute teach, who happened to be black, asked a student, who also happened to be black, "What would happen if we axed so and so this quesiton?" His reply was "Nothing. If we axed them they would be dead."
The author is simply lying. Rush says "ax" instead of "ask" practically every time he utters the word on the air, no matter the circumstances. It's a running joke of his. To claim Rush only says "ax" when discussing a subject that somehow involves black people is complete BS.