I personally agree that what David Icke is spreading is a bunch of nonsense. But I'm against suppressing him because otherwise I can't maintain a logically consistent belief system. That is to say, as soon as we can ban the lizard guy, we can also ban a lot more viewpoints that are not quite as controversial / outright crazy but straddle the line.

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"?