So the COB and XO on a boat on the Pearl waterfront banned porn on board (yeah, that went over real well as you can imagine) but prisoners can sue to get it?
"Suing" and "Winning" are two entirely different things.
Prisoners have vast amounts of time on their hands and unfettered access to the courts to sue over any stupid shit they feel like under habeus corpus or any 1st/5th/8th/14th Amendment formulations they can cook up, including inventing a religion requiring them to eat steak at least once a week (Really). Some percentage of them really does expect to get what they're suing for, but a majority of them just do it to screw with the prison administration and get the odd change of scene for their infrequent court appearances. It doesn't cost them anything, since being prisoners the State and Fed courts pretty much don't have any choice but to waive all the filing fees or else get themselves in an actual violation for denying access to the courts.
The vast majority of these cases get nowhere, they just waste a lot of resources in the process of getting there.