So, here is the comment I provided:
As a television news anchor, Brian Williams is as much a television personality as he is a journalist. All newscasters are media personalities as well as reporters, so that the truthfulness and factual accuracy of their reporting matters less than their overall image. We refer to their credibility, and that is a quality we look for in actors, to fool us into believing they are the characters they portray.
By telling tall tales, Williams has irreparably damaged his ethos as a TV news anchor. If he were a print journalist, it wouldn't matter, because newspaper reporters are nothing more than a byline, but on television it's his look, the sound of his voice, his overall manner and presentation of self, and his celebrity persona that establish his credibility. In this sense, he is as much an entertainer as a journalist, which is reinforced by his many appearances on comedy talk shows.
The irony is that he was chosen as NBC's anchor in the first place in large part because he looks and sounds like a traditional TV news anchor, he plays the part well. So the moral of the story is that TV giveth, and TV taketh away. We need not feel too sorry for him though, as he can still serve as a pundit on cable news, perhaps even the host of his own show, the credibility standards of cable news punditry being so much lower that network news.
As you no doubt know, Williams soon afterwards went off the air, is currently serving a six month long suspension (or at they say in show biz, he's on haitus), and it remains to be seen whether he will ever return as an anchor. My prediction is, he won't.
And I hope you don't mind if I throw in another plug for my book, Amazing Ourselves to Death: Neil Postman's Brave New World Revisited, which includes a discussion of Postman's original argument that television reduces journalism to just another form of entertainment, because this is just one more example of that sort of thing. You don't have to be an Einstein to understand what the Brian Williams story. Frankly, it's a no-brainer.