Yeah that’s usually a bad start xD
That entirely depends on what kind of producer you are. There’s loads of different ones there. Ranges from “only” giving monetary support all the way to being super hands on and part of, if not the main, creative vision.
Looking at some of his work I reckon he fits somewhere close to the latter part of the spectrum 
He’s nowhere on the official crew list as far as I can see apart from as a writer of the original. I just kinda find it hilarious that he was so convinced it couldn’t be made into a film that he didn’t want his name on it at all 
Also just a side geek out from moi, I absolutely love confessions. Still one my favourites films (and books) out there, simply because of the concept of it.