While an interesting idea, I would say releasing the book before the album wouldn't have worked. Why? Just look at the way most book-to-movie translations work out. 9 times out of 10, most people will say "the book was WAY better" and I'd wager something similar would've happened in this case. People would be wondering why certain plot points in the book weren't used in the music.
Of course, if the album was written/recorded first, the argument would be that those things were added after the album was done. But then the question would be "why didn't JP re-write the album to include these plot points?" And even then, it would still put JP in an awkward situation since he might read the story and think some of the things the author included were better than the way the story is presented in the music. So then he would have to decide whether to re-do parts (or maybe even all) of the album or not, and if he did, he would probably need to give the author credit as well.
So while all hypothetical, I think the way things worked out was probably for the best, aside from the personal issues I have with the album, but that's a whole other discussion that's been beat to death already in numerous threads...