This is why I believe the 'opt-in/out' switching should be as seemless and accessible as possible - if it is, then to my mind this is no closer to censorship than the film classification system.
"By default the state assumes you don't want to see sexual content; if you do - thats fine by us"
Note that I'm saying this is how I see it balancing with civil liberties - there is of course the chance that it DOESN'T work out like this in practice.
