Not that such things aren't without their own flaws, but I like to toy with real-world analogies when thinking about computer crimes. One that seems applicable here is that of a library -- there are stacks of books, and if you know where to go you can read any book you'd like. If a librarian wishes for a book to be inaccessible then the easiest thing to do is to remove it from any indexes and stop telling people about it, but they're still fully within their rights to browse every book till they find what they're looking for. Absent some sort of additional access control, disposal, etc, it would be hard to blame a patron for reading that banned content even if they started their search with the express purpose of uncovering such banned material.