I was a bit too tired to give reasons why… I've said this before and I'll say it again. (oh and I am a big reader)
First off the story is reportedly terrible, normally if you have a bad story, you don't publish it.
No matter if it would be billed as Ghostbusters III the book, or just a GB novel, the story involves new characters to be GB's (not even Extreme Ghostbusters), which would not be too thrilling for the reader.
While I suppose it could work, a novel is not exactly the best medium for Ghostbusters.
If any future GB project is to be done, it could splice some of this material.
I know people will still say ‘but it’s written, it won't be a movie, so why not make it a book?' Believe me, it's not worth it. It's all in too strange circumstances anyway. Oh well, I guess it doesn't matter if my opinions are right… the book will never happen so I win that way (sorry guys).