It looks like PBS's resident liberal commentator Bill Moyers is taking it on the chin. According to the Slate piece to which I'm linking below, while working for LBJ, he was involved in campaigns to ferret out homosexuals in government and in Goldwater's campaign. He was apparently also involved in other unsavory practices of the Johnson administration, including bugging Martin Luther King's private life, surveillance of civil rights groups at the 1964 Democratic convention, and planting shills in press conferences. This kind of thing should come as no surprise. He was a special assistant to LBJ for Christ's sake, and when you wallow with the pigs, you're going to come out covered in mud and shit.
Of course, though Moyers is derided by the right wing as a liberal, he is no such thing. He is, in fact, an old-fashioned conservative. As such, he would have adhered to a chivalrous notion of loyalty. LBJ being his lord and master, Moyers would have done his bidding as any good vassal should.
http://www.slate.com/id/2211601/pagenum/all/#p2