David Icke is not spreading information. He's spreading nonsense about lizard people. That's objectively true.
And just to head this off, the dimension of palatability to advertisers is separate, and if a site chooses to quarantine or whatever, so be it. I'm speaking merely from a framework of, "is this the kind of society we want?", as opposed to, "is it feasible for a profit-seeking corporation to adopt such an open policy"?
What should be protested is that there isn't really anywhere else to go -- and the best form of protest is to build it.
This is the issue, if you are saying YouTube should allow all content then you need to be consistent and allow all content. If not you really just disagree on what content should be censored, but then you can't make this out to be a censorship vs free speech debate, because you agree on censorship, just not on what gets censored.