Juan Williams Becoming Conservative: Left is close minded, harsh and vicious
One of the benefits of these past couple years is the explosion of the myth Republicans are the intolerant ones.
The money quote starts at the 50sec mark.
Lieberman being run out of the party because he was the only D to support The War on Terror made it clear how far gone the Left had become.
Its stuff like this that must have pissed-off the NPR folks. Flipping through the comments you find him called an Uncle Tom, sell-out, or both. I think many at NPR probably thought the same and were looking for something to give him the pink slip. Certainly his firing wasn't about one incident where he expressed his honest opinion.