The ebooks distributed on the Kindle Store are distributed under a license that Amazon has negotiated. The GNU FDL does not permit redistributing under a different license. If the person submitting the book could assert that he was the author, and held copyright to the content, that would be one thing. If it is community authored, and edited by this person (as was actually asserted), Amazon would be opening themselves to actual legal liability from all of the other authors.
It's insane to me how many people who assert that Free Licenses are useful in such situations. This is the same as attempting to put some GPLed software on the App Store. It can be done, but only if everyone agrees to offer Apple an alternate license.
Probably the bit about how they can't distribute it with DRM and must allow people to easily copy it from that point of distribution. I don't know for sure how free kindle e-books are distributed, but my gut tells me that it's the same way that non-free e-books are. If there is DRM preventing me from copying that e-book to another device, modifying that e-book, etc, then it would be in violation.
The fact that it's a settling doesn't solve the problem. If they decided to build whatever infrastructure was required to flag copyleft content and then essentially lock this setting, they might be in a better position. It still doesn't protect them completely. If the author fails to include the license in the book, for instance, they're in deep water. So the important thing to remember is that they can't get into this game lightly. It takes a bunch of work.
The GNU licenses are not designed to facilitate maximum spread of the content. They're designed to enforce sharing. Unless Amazon wants to get involved in that enforcement, they really can't touch this stuff.
The ebooks distributed on the Kindle Store are distributed under a license that Amazon has negotiated. The GNU FDL does not permit redistributing under a different license. If the person submitting the book could assert that he was the author, and held copyright to the content, that would be one thing. If it is community authored, and edited by this person (as was actually asserted), Amazon would be opening themselves to actual legal liability from all of the other authors.
It's insane to me how many people who assert that Free Licenses are useful in such situations. This is the same as attempting to put some GPLed software on the App Store. It can be done, but only if everyone agrees to offer Apple an alternate license.