I think it's a deplorable and dishonest idea. The ploy is, of course, to pick a target of a kind that nobody would ever want to defend, and yet the real range of material that would be either blocked or land in a grey zone is much wider than actual kid porn or hardcore rape depictions that "are promoting r/l rape" (in Cameron's mind, any violent scene with sex or D/s fantasy is likely "inciting to r/l rape"). The way Cameron and his backers (esp. the Daily Mail) phrased what they are fighting, anything that even touches on too overt depictions of sex, particularly non-vanilla sex, could get blocked at some time. Youtube has masses of film trailers and pop videos that would land over the red line, the same with pictures on many blogs or at Wikipedia. And any kind of forum or picture sharing site such as this one, Instagram, Flickr or various role play/games related sites would be blocked too. Not to mention, lots of sites set up to provide information, counsel and help around sex habits, STDs, trafficking and so on.

That kind of filtering is something I would unconditonally want to handle myself, it's not the business of any government, church or ISP.