Whistlestop-- I agree with your point here though, I don't know that it was the "liberal establishment" that was advocating the sort of violence, Maoism, and general intolerance that "Revolution" seemed to speak out against--and, I remember that there were quite a few who felt that that song seemed to mouth all the "Liberal establishement" cliches--

As to the co-opting, I think musicians are just as inclined to jump on a political bandwagon as the otherway around--it took me years to forgive Sammy Davis, Jr. for kissing Richard Nixon--

Bruce Springsteen did tell the Conservative Republicans (was it the Reagan people or the Bush people?) where to go when they asked to use "Born in the USA", which is better that Blues hero, B.B. King, who recorded an album with Lee Harvey Atwater, which was Atwater's reward for the despicable Willie Horton campaign that elected George Bush-

The combination of "folk" music and politics is nothing new, the 14th century Flagellants sang religious songs in the their native languages (a revolutionary act in itself, since Church hymns were in Latin) as part of their public religious processions, during which the beat themselves bloody in a religious frenzy--

Of course, Martin Luther also wrote his hymns to folk melodies--