Who is doing the editing is extremely important. If a newspaper declines to publish a white supremacist screed in their op-ed column, that is not censorship. The screeching racist can always try and publish somewhere else, or publish themselves (online or in print), or yell in the streets. But if the government intervenes and tries to force/prevent any of those things from happening, that's censorship and it's unconstitutional. Completely different ballgame. It drives me up the wall that people think those cases are "equivalent".