How thin is the line between "rantings of a paranoid conspiracy theorist" and constructive criticism.
I don't know how thin the line is, but in this case it seems quite evident that constructive critism is not part of the equation. Anyone who read the old board for more than a few moments would come to the paranoid conspiracy theorist conclusion I would imagine. The problem with CC is that he simply doesn't, and isn't likely, to have any legitimacy or credence. Even if any/all/some of his allegations are true, no one is likely to believe him simply because of his approach. That's the difference between truly believing in something and the electronic equivalent of hiding in the shadows sniping.
As far as actual censorship goes I hate to come down on the side of it, and won't, at least not in this case. I'd prefer to think of any removal of posts here as good board management. Freedom of speech is a wonderful right. But it does not give anyone the right to scream "fire" in a movie theatre, nor does it give them the right to scream anything they choose, at least not without getting ejected from the show. Removing posts with no discernable value, or related to the topic at hand should be an acceptable practice. Much the same way we would expect other inappropiate posts(behavior), ads/porn/racism, to be removed.
As far as who decides that. That is certainly the job of the board operator if Dave is gone (Dave are you gone??) someone should be minding the store, not just because of CC, but should any posting problems arise, not to mention the day to day care and feeding of the board. As long as the rules are known up front, applied evenly and without prejudice there is not likely to be a problem.