NCQ - and if you are a bookseller by trade you could decide not to sell books that pro-actively seek to encourage people to hit babies.
I grapple A LOT with issues of free speech and censorship - it's important to my area of work, and I have often persisted with public dissemination of things which either some members of the public (many times) or a lawyer (twice) or the law (once) sought to silence. We have been attacked by agencies with 'an agenda' in the mainstream press. As Director of the organisation I work for it is my responsibility to decide how matters of quality, taste, legality and morality impinge, to take a decision, and then take responsibility for that decision. Sometimes it has been to let an artist 'do their thing', and let the public and the artist negotiate those matters, sometimes I have taken a strong line of my own. We have endured arson threats and (twice) demonstrations against work we have supported. I answer conflicting letters about the same piece of work.
If I was a bookshop I would not choose to sell this book. Would I be setting myself up as censor, or just choosing not to stock it? Amazon are a commercial organisation. If they don't sell H Potter, they will lose zillions, and anyway, the protestors are loud, nutty, but still a MINORITY. They probably get all sorts of protests about all sorts of stuff - as I do, in my small way - and of course they take no notice of much of it because it is not in their commercial interest to do so, and the opinion is not one they feel strongly about, or they actively disagree with it.
I think what you say about free speech enabling progrssive ideas to best evolve is crucially important - but by now most of us have evolved beyond this sort of thing...and this isn't about a theoretical proposal - it's an instruction manual. That's why i would take a campaigning stance about selling it if i were a bookseller.
re bombs and homosexuality - to a certain extent, i think adults are grown up enough to deal with the world they vote in, contribute to, campaign in...children can't do that, and while this book is sold, the children who are abused as a result are perhaps paying a v high price for being the guinea pigs on which progressive ideas are tested.
I am still in 2 minds about this - not dismissing your arguments by any means. Just postulating back.