I gave a government example, as that's what we were talking about. Censorship just requires power, and government power is the most important and obvious kind because governments are monopolies over large numbers of people. But yes, you also, having power over your kids, can censor what they see.
But if every individual ISP refuses to host the KKK because they'd just rather not do business with bigots, then that's not censorship. It's just freedom of association.
If the 8chan guy tomorrow decided to shut down and nobody else wanted to host the pedophiles, that isn't censorship. They can buy a piece of land and make a pedophile clubhouse. They can buy a printer, make pedophilia leaflets, and distribute them in the town square. But if nobody wants to help them do that, it isn't censorship, because nobody is exercising power over the pedophiles, just over themselves.