For many years I tried to explore the so-called "35,000 library books" for the detainees. One funny thing is that the number has not changed over the last 7 or 8 years, despite the fact that books are regularly donated to the library. The other funny thing is that the books are not generally available to the men. Although my information is a little out dated it still appears that a small number of books are rotated through to the men. If I send a book I can notify my client and he can ask for it. But if I don't notify him he of course will not know the book and will not see the book.
And the standards for what books can be made available at the "detainee library" are crazy. We can't have the men reading "The Gulag Archipelago" (too much similarity to the soviet system) or "The Trial"- (again too many parallels to our system which allows the men to be held for unknown crimes.)
But it is quite OK to have the Harry Potter series.
Well anyway, someone has tried to figure out the warped and secretive library for the men at Guantanamo. You can read about it here. And maybe the books that make it to the library pass this test "the library only allowed materials that were “culturally sensitive, non-extremist in nature, and generally non-controversial.”
But mostly it seems that the people doing figuring out which books the men can read and which are too "controversial"... havent read the books themselves.