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.
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.
Which is still completely irrelevant because this document is licensed under the GFDL.