What's controversial about saying the Republicans & their Tea Party allies are racist?

I'm sure you have already heard that NPR CEO & President Vivian Schiller has resigned following the resignation of NPR Senior VP for Fundraising Ron Schiller (no relation) due to "controversial" comments he made:

Tea Party people aren't "just Islamaphobic, but really xenophobic, I mean basically they are, they believe in sort of white, middle-America gun-toting. I mean, it's scary. They're seriously racist, racist people."

What I don't understand is why telling the truth is controversial.

http://www.npr.org/blogs/thetwo-way/2011/03/09/134358398/in-video-npr-exec-slams-tea-party-questions-need-for-federal-funds