1. They know books like Fahrenheit 451 appeal to the left.
2. Their entire modus operandi is: "own the libs"
3. They know a liberal finding real-life nazi flyers in such books will confuse, frustrate, or anger libs.
4. They "win." It's as simple as that - making the libs cry. If, for some crazy reason, it recruits another nazi, then they're doubly successful.

<sigh>