Censorship of books in U.S. prisons

From a story in The Guardian:

There is “widespread censorship” of books in US prisons, according to a report submitted to a UN human rights review, which details the banning of works about artists from Botticelli to Van Gogh from Texan state prisons for containing “sexually explicit images”.

The report from two free-speech organisations, the New York-based National Coalition Against Censorship and the Copenhagen-based Freemuse, to the United Nation’s (UN) Universal Periodic Review states that the Texas Department of Criminal Justice (TDCJ) lists 11,851 titles banned from its facilities. These range from the “ostensibly reasonable”, such as How to Create a New Identity, Essential Throwing and Grappling Techniques, and Art & Design of Custom Fixed Blades, to what it describes as “the telling”, including Write it in Arabic, and the “bizarre” (Arrival of the Gods: Revealing the Alien Landing Sites at Nazca was banned for reasons of “homosexuality”)...

“Of the 11,851 total blocked titles, 7,061 were blocked for ‘deviant sexual behaviour’ and 543 for sexually explicit images,” says the report, naming artists including Caravaggio, Cézanne, Dallí, Picasso, Raphael, Rembrandt and Renoir among those whose works have been kept out of Texas state prisons.

“Anthologies on Greco-Roman art, the pre-Raphaelites, impressionism, Mexican muralists, pop surrealism, graffiti art, art deco, art nouveau and the National Museum of Women in the Arts are banned for the same reason, as are numerous textbooks on pencil drawing, watercolour, oil painting, photography, graphic design, architecture and anatomy for artists,” states the submission, with prohibited literary works by Gustav Flaubert, Langston Hughes, Flannery O’Connor, George Orwell, Ovid, Philip Roth, Salman Rushdie, John Updike, Shakespeare and Alice Walker also on the banned list.

More at the link.  The eagerness to ban pornography puzzles me.  These prisoners are capable of hiding razor blades in their mouths and knives in their rectums, and the  authorities are worried that the images might corrupt their minds or they might waste their time masturbating??