You know that there are some books that people think you should not read, books where the simple act of reading them constitutes a hazard to life or liberty? But we're not talking about censorship. No, this is a case of the book's very author deciding that reading his book in public is dangerous. The very people who put pen to paper (or finger to keyboard) have decided that it is irresponsible to send you into the world with a copy of their works without some way to keep you safe. They like to give you the idea that you will need some kind of disguise for your book and so provide one in a sort of factory-installed Book and Switch.