More on Creative Writing and IP Rights

I just finished reading The Future of Us a young adult techno-romance story by Jay Asher and Carolyn Mackler.  Basically, the conceit of the book is that a couple of teenagers in 1996 stumble upon a website that lets them access their futures via Facebook.  It’s a cute idea and gives some perspective on how the pre-Facebook teen generation might have responded if confronted with their Facebook pages from 15 years in the future.

The book obviously refers to “Facebook” a lot and also reproduces the format of Facebook entries, although the posts are fictitious ie all written by the main characters’ future selves.

At the end of the book, the authors acknowledge the help and support of Mark Zuckerberg, suggesting that they asked his permission to use Facebook in the way they did in the story.

My question is whether they could have written the book without such permission and not infringed Facebook’s copyrights or trademarks.  I know it’s always a good idea as a practical matter to seek permission rather than to wait and see if someone sues you, but would Facebook have had any valid I.P. claims if no permission had been sought?  Facebook is extremely integral to the plot of this book ie it’s not just referred to in passing, but nevertheless it’s difficult to see how as a matter of theory there could be valid trademark or copyright claims here.