It's alright harping on about freedom when it's copyrighted material, but I don't know many people who oppose the blocking of child pornography or snuff on the same grounds.
Except for the fact you might block legitimate things on the grounds of these things, these things are never about protecting the children there all about control of things the government doesn't want you to see, and occasionally they also block things that are legitimate as well on these grounds. We should fight whenever it happens because its a free internet and the moment you close doors on it is the moment its gone.