Violence, free speech, and the law
In this sense, the story is not entirely different from the tale of the professor who told her students that their free speech rights extended to vandalizing an anti-abortion display. Of course they don't, and no sensible person thinks it does.
Or perhaps that story is more similar to Michelle Malkin's publishing people's personal information, and her followers' decision to send some peace activists death threats. Death threats aren't protected speech.
What it is not similar to is the recent emergence of retired generals criticizing conditions within the Pentagon, and the leadership of Secretary Rumsfeld. It's no more improper for retired generals to speak out now than for non-generals to speak out, or indeed for generals to run for President. Kevin Drum is silly and wrong to argue that there's some important problem raised by retired generals joining the public debate.
In fact, I don't see what the problem would be with generals expressing their disputes over policy. Doing so on CNN would be inappropriate, but that would be inappropriate for people within the civilian leadership, too. The subordination of uniformed leadership to civilian leadership is guaranteed by the fact that the President makes the final decision, and the Secretary of Defense passes his orders down. Advise should flow up openly. That's what free speech is about.