SmallFurryCreature, I disagree with your statements about how (summarized) this IP ban is a step on a slippery slope toward arbitrary censorship. Your handwringing is emotional but not cleanly argued. Here are my responses:
Your statement that the CoS is being shut out of Wikipedia is false, and you have received a number of responses pointing this out. In effect, Wikipedia is merely making it more inconvenient for CoS to vandalize their content. Vandalize? Yes, see the next point:
Wikipedia has instituted a process for submitting information (including changes thereto) and for keeping content as factually correct as possible, given the circumstances. The CoS has knowingly broken the rules. Stopping CoS, at least in part, from subverting the proven effective process, is not just Wikipedia's right but their obligation. Most users operate on the assumption that Wikipedia's content is factual, provable and unbiased. Their process has been shown to be effective, on the whole, thus so as not to disappoint their user's expectations, they are applying said process.
Wikipedia represents "the knowledge of the world." Unless and until they manage to "clear the planet," the world is bigger than Scientology. What they're doing is interfering with the rest of mankind documenting the current state of their knowledge. If CoS wants documentation of their own view of things, then they're welcome to set it down in a less global venue.
The fact that CoS willingly, knowingly and repeatedly break the rules must make the rest of us question their ethics. In fact, Scientology ethics do perceive Scientology to be above the laws of the rest of the world, based on the notion that the CoS is more capable of making informed decisions on behalf of the rest of humanity. It is precisely because of this self-righteousness, which extends logically to demand the overthrowal and replacement of currently acting governments, that the CoS has been declared illegal/unconstitutional in a number of enlightened countries, of which the USA is unfortunately not one.