I had read and backed the book in question and while I agree that the contents of said chapter were very strong indeed, the book was clearly labelled as ADULT.
So what makes it unsuitable? Well it's political if you ask me. The book deals with child abuse and pornography, and with that nasty case going on at the moment, it could be seen as too close for comfort. Well, it certainly wasn't a comfortable read, but it was expertly written and clearly reflects what goes on in some dark corners of our society. Art mirroring life.
Hope they reconsider. We can censor ourselves. If you don't appreciate it, don't read it.