Two things:
One. Freedom of speech is a first amendment right to protect you from censorship by the government and the government only. Anyone, anywhere running their own service is fully within their rights to boot you off.
Two. A sleazy pickup artist book isn't anywhere remotely near any previous works of banned art. I would consider something as awful the film Cannibal Holocaust to be fine art before I used that term for some idiotic kickstarted pick up artist book.