Imus is a pain - rarely listened to him, and when I did in the morning while switching channels, I found him to be boring. When Imus made those comments, and it was one of many, it was just the tip of the iceberg. Now he is gone for now, probably will be back eventually, but it is a warning to all others to be careful what you say.
I think the problem was the Imus directed it to a group of girls who were smart, a winning team, and nothing to do with politics. Innocent group, which backfired like crazy on him.
As for the CEO of Am Ex being black, that doesnt matter. Imus is a PR nightmare right now, he needs to make a spin on something asap, which won't matter.