Don't play the game when the rules are rigged
It's fairly obvious what David Brooks is trying to do.
"What's happening to Lieberman can only be described as a liberal inquisition," writes Brooks. "Whether you agree with him or not, he is transparently the most kind-hearted and well-intentioned of men. But over the past few years he has been subjected to a vituperation campaign that only experts in moral manias and mob psychology are really fit to explain."
"I can't reproduce the typical assaults that have been directed at him over the Internet, because they are so laced with profanity and ugliness, but they are ginned up by ideological masseurs who salve their followers' psychic wounds by arousing their rage at objects of mutual hate," Brooks adds.
Brook's is trying to perpetuate the frame that the only people who oppose Lieberman are crazed, left-wing nutjobs. This is how the right-wing noise machine keeps Democrats in line, "do what we think you should do or we will throw you to the crazed, left-wing wolves." And a lot of Democrats buy into it.
Worse, a lot of opponents of Lieberman do as well, by simply arguing against the Brooksian frame.
Brook's argument doesn't deserve reasoned response because it is not a reasoned argument. He and others do not provide evidence that Lieberman is the victim of a crazed, left-wing inquisition. He simply states it as fact and then hints about the things he has seen which prove it but which he cannot reproduce because it might offend his reader's delicate sensibilities.
Don't fall into the trap of trying to refute the "crazed, left-wing nutjobs" frame because doing so will only give it weight. Simply re-iterate the argument against Lieberman. If your argument is good it will win people over. But if you get pulled into a shouting match with people like Brooks you will just convince the audience that the "crazed, left-wing nutjob" frame may have some truth to it.
Our argument against Lieberman is strong enough as it is. We don't need to waste time refuting nonsense. Just call it nonsense and move on.