The answer to crazy conspiracy theories is not censorship. It is information.
In the United States, because of our cherished First Amendment, there is no such thing as 'Hate Speech'. There is just speech, which is protected. If you don't like what someone is saying then don't listen to them. If you believe that their speech poses a danger to society then use your right to free speech to convince everyone else why they are wrong.
The answer to crazy theories and disgusting rhetoric is intelligent debate. It is not shouting people down, getting people banned, or preventing speech.
When you shut people down and prevent them from speaking what you have done is to leave them only one avenue by which to express themselves, and that is violence.
The monster in NZ states in his manifesto exactly what his plan was. The purpose of his attack was only peripherally to kill people he didn't like. His attack wasn't even directed at NZ, though they have been following his plan as if they were co conspirators of his. His attack was directed at the U.S. His purpose was to push the left into banning weapons, censoring speech and taking away rights, because he knew the left doing this was likely to cause the right to stubbornly resist such actions. Initially politically and legally and eventually violently, should the left persist in their actions to curtail rights. NZ is moving right along that path.
Meanwhile, as everyone here can attest, people who want to see the banned information can see it because The Net interprets censorship as damage and routes around it. (John Gilmore)