Batshit crazy, yes. Brainwashing, no. You don't get brainwashed by reading a book or a site on the internet. You can, however, get lured into an organization that will, in fact, brainwash you (for example, Dianetics, leading to Scientology, or "What the bleep" leading to Rathma). That doesn't appear to be what's happening here (though anything is possible). It's
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Coercive Persuasion and Undue Influence