xkcd rarely puts out a terrible comic, but they did it again today:
The problem, of course, lies with the misguided notion that our rights are something that only the government can suppress. No, sadly, it is anyone in a position of power who may seek to deprive you of your rights. Government is merely a more loathsome oppressor due to their self-granted monopoly on the use of force.
And that power can indeed be abused to silence things like web hosts. It matters not one whit if the order comes from the government directly, or indirectly via "morality" laws (e.g., wholesale prohibitions on gambling and porn sites due to jurisdictional ambiguities), or just hosting providers collectively deciding no "assholes" should be allowed to have their say. When you prevent the potential of there being consequences, you've gone too far.
My impossibly stupid point is that you should not feel you are in the right when you keep other people from hearing something you don't like. No matter how small the forum is, if it has any respect for free speech at all, it should allow people to criticize it. I'm not saying assholes should be given carte blanche for any wild rantings that they vomit up (I, for instance, readily cull the spam comments here), but merely that it is a free speech issue if any X has the power to keep you from saying "Fuck X".