Those who defend Cindy Sheehan by saying "she has the right to speak out" are engaging in a poor defense of her whinging that contributes nothing to the discussion of the MERIT of her statements. There's little merit in them, but that's not the point, as Jonah Goldberg notes:
if you want to defend somebody's controversial statements, saying "so-and-so has the right to his opinion" doesn't get you out of the gate. It just sucks up air and fills space. Intellectually, it's got the nutritional value of Styrofoam. You might as well say "Oo-ee-oo-ah-ah, ting-tang-walla-walla-bing-bang" instead and then move on to your next point. It's not interesting, not smart, not insightful. Saying Cindy Sheehan has a right to criticize the president is like saying she's a carbon-based life form: True, but utterly beside the point.
Indeed, the "right to speak" defense in the face of criticisms of a speaker's content has some implicit premises, most of which are intellectually immoral:
The great irony is that the people who resort to such "arguments" (they're really just insults) are the ones questioning free-speech rights, because they are suggesting the criticism was inappropriate and, in some vague and stupid way, unconstitutional. Right? That is the upshot of what they're saying. I mean, if you immediately assert that someone has the right to say something as a way to rebut criticism, aren't you implying that such criticism violated their rights — which is, by definition, unconstitutional.
The paranoia enters into it when you consider the nature of the accusation. If you immediately assume that criticism from the political Right is tantamount to questioning someone's constitutional right to speak in the first place, what you are really saying (Pace Dan Savage) is that if you scratch a conservative you'll find a Storm Trooper just under the surface . . . That so many on the Left seem to believe this says a lot about the intellectual and psychological state of Lefties while saying nothing of interest about conservatives . . . Not only does the "I have the right to speak" tantrum dodge the merits of specific criticisms, it starts from the assumption that as a matter of first principles left-wing protest should never be questioned.
Indeed, that's the reason the Left has rallied so fiercely behind Cindy Sheehan. Wedded to a form of identity-politics logic which says some "authentic" voices cannot be questioned and inauthentic voices need not be listened to, these hardcore left-wing activists love Cindy Sheehan because they think she's above reproach. They immediately resort to the argument "How dare you question a woman who lost her child!" Sheehan's loss is obviously a terrible one. But the death of her son does not make her anymore qualified to rant about Israel and oil tycoons controlling American foreign policy than it would be if her son was alive. But her backers do not care, indeed they don't think anyone has the right to even point this out.