It seems like this would be common sense.
But, we have seen in the past guards and inmates take photos and get autographs of celebrities who are incarcerated. In the new age media world those photos can end up on TMZ quickly, so the jail is trying to stop it before it starts.
According to TMZ ironically, the jail staff has been informed that if anyone is caught getting a photo, asking for an autograph or giving Hernandez special privileges they will be fired. A source inside the jail, says so far Hernandez has been a model prisoner.