That is the confusing part, Amazon talks about 'selling' it and he talks about 'managing copyright'. So it seems like they are talking about two different things, tied together by the liability of selling someone else's copyright protected material. I was looking for the response that said,
"Yes this stuff is available for free on the web, and it is available for free in this kindle book, I've just collated it into Kindle form to make it more accessible for people. All of the rights holders have explicitly allowed this use."
I can't see that anywhere.
edit: looks like only amazon refer to it as being 'sold', can't see the author mention it.