I think it is the librarian in me that doesn't believe in censorship, because once it starts, who knows what will go on the banned book list? However, I do think some caution should be used when dealing with children, and parents should decide whether something is appropriate for their children.
If I had young children using my Kindle or buying p-books from Amazon, I would put on the parental controls and restrictions.
I don't think the same restrictions should apply to adults, even if I find content to be reprehensible.
I think Amazon should only have to worry about delivering what is legal,