Another angle to look at is Imus' history. His inclination to use racial slurs, out of the context of comedy, are well known in some circles.
For example, one comment by Imus that ran in Time magazine..'when speaking about Gwen Ifill, the African-American PBS anchor who was then the White House correspondent for the New York Times, he said,"Isn't the Times wonderful? It lets the cleaning lady cover the White House." ' Ha-Ha.
I mean he's a dull old coot looking to remain cutting edge and he just ended his career. Good riddance. Maybe he can go clean houses now.