None of this has anything at all to do with the First Amendment.
Seems like there is a serious back-story that hasn't fully been leaked yet. Here is one Wikipedia one explanation:
"According to NPR, the remarks were "inconsistent with our editorial standards and practices, and undermined his credibility as a news analyst with NPR."[8] As to the reason for the termination of Williams' contract, NPR’s CEO Vivian Schiller offered the following comment, "News analysts may not take personal public positions on controversial issues; doing so undermines their credibility as analysts".
rfenst wrote: