Selling Al Franken's books

Law professor Eugene Volokh says the Fox lawsuit against Al Franken over the phrase "fair and balanced" in his book title is much weaker than even Spike Lee's claim to Spike TV. What's weird is that a big company like Fox would help Franken sell books with such a cheap publicity stunt. Unless they really believed their case, which would be even sadder. I'm no legal scholar, but isn't commentary that makes fun of Fox (or any other political entity) just about the most constitutionally protected speech there is?