Even if it is sold for $0.00, I wouldn't expect that to remove Amazon's issue with it. Whether or not the book is generating income, the person who "published" it does not have demonstrable rights to its contents.
Which is completely irrelevant because whoever does have the original copyright has already licensed them to everyone under publicly available conditions.
The GPLv2 has made it clear something can be made freely available to the public, yet still have redistribution conditions. So, simply being "licensed to everyone" does not also grant distribution rights to everyone.
I'm not saying the GPLv2 withholds distribution rights; rather, it grants them conditionally, and if you can grant them conditionally you can withhold them.
