One important thing to remember is that these are fiction books. Events in these books are not really happening. Once you start censoring books because of things in them, fictional things, it's quick slope getting rid of detective stories because they have a murders in them, rapes, or anything else. There're plenty of mainstream books or classic pieces of literature that have unsettling things in them.
There are a lot of books out there that I find disturbing. My solution is I don't read them. I feel perfectly fine letting others police themselves, and letting other parents police their children.