Interesting idea. But the real censorship that's coming down the pike is of the "voluntary" and "cooperative" variety. And it will be the ISPs rather than the social networks that will be doing it after being "encouraged" to take on more "responsibility" by several governments.
So whether you're social site is on FB or G+, or it's hosted on some decentralized P2P system going through an onion router, it's only a matter of time before it can be identified and shut down. Because the backbone and conduits are provided by governments and corporations.
Many people assume there's nothing that can be done to effectively stop hackers. And while that may be semi-true with the Internet the way it's currently implemented, there's nothing to say this particular version of the Internet
will be the one we all end up using ten years from now. Either way, it's a sure bet tomorrow's Internet will be nowhere near as open (by design and law) as our current one is.
At best, Anonymous' social network will be a temporary stopgap unless Anonymous starts stringing its own fiber and putting up its own satellites. (Oh! Do they know you need a government issued license to do that?