If you forget that Franken is a leftist schmuck, who hates anybody to the right of Lenin, and you forget that FoxNews is considered by many to be on the right, then the cover is deceptive.
The cover is not deceptive if you can tell just by looking at it that it is a parody of FoxNews. However, FoxNews maintains publicly that they are not a member of the VRWC. In fact, they publicly maintain that they are not on the right at all, but are, rather, "Fair and Balanced".
So, based on the cover alone, you have FoxNews personalities on the cover with a statement that the book is "Fair and Balanced". A reasonable person who does not necessarily subscribe to Franken's political views could well conclude that FoxNews was a party to the production of this work, rather than the target.
The burden of proof is on Fox to show someone could be confused. And, while I know what you're trying to say, I bet that in a year you couldn't find five people who honestly would be confused as to this book's agenda.
There was a recent case in the south where a sex novelty shop (toys and such, I think) called itself "Victor's Little Secret". Victoria's Secret sued. The court ruled no reasonable person could have thought the two were related.