The article doesn't address how the prison system will enforce its internal rules/policies on the outside world, social media. Running a web page about a specific prisoner's complaints is legal, so I don't see how they can stop it.
Their motive, of course, is transparent. They don't want non-victims of the legal system to know what really goes down by hearing first-hand accounts. They want to filter such knowledge first through lawyers, then water it down again through the media, leaving the information so diluted that it has no effect on readers.