Is Juan Williams firing by NPR an assault on free speech?

News Analyst Juan Williams' responded to his dismissal today by National Public Radio (NPR), by calling it "a chilling assault on free speech by self-righteous ideological, left-wing. … They loathe the fact that I appear on Fox News."

Williams was fired after appearing on Bill O'Reilly program on the Fox network. O'Rielly had asked Williams about comments pertaining to his own controversial remarks made on the "The View" about Muslims.

Williams responded by saying, "Look, Bill, I'm not a bigot," Williams said. "You know the kind of books I've written about the civil rights movement in this country. But when I get on a plane, I got to tell you, if I see people who are in Muslim garb and I think, you know, they are identifying themselves first and foremost as Muslims, I get worried. I get nervous."

He continued, "Now, I remember also that, when the Times Square bomber was at court, I think this was just last week, he said the war with Muslims — America's war — is just beginning. The first drop of blood. I don't think there's any way to get away from these facts.

"But I think there are people who want to somehow remind us all — as President Bush did after 9/11 — it's not a war against Islam."

Williams told O'Reilly, "You've got to be careful" to point out that there are good Muslims. He noted that Americans don't blame Christians for the actions of Timothy McVeigh in the Oklahoma City bombing.

Should NPR have fired Williams although his comments were made while he was off the clock? Is it a chilling assault on free speech?