Perhaps the prison authorities see value in the stories. It could be that these stories are part of a rehabilitation program. If the prisoner is sharing positive, educational, or self - reflective stories, they might be rewarded with extended time for activities like reading or writing more stories. This can also be a way to encourage prisoners to express themselves and potentially heal through the process of storytelling.
It could be that the stories are part of a cultural or creative project in the prison. Maybe the prison is promoting art and literature among inmates, and the prisoner's stories are considered valuable contributions. By giving the prisoner extended time, they are motivating the prisoner to continue creating. Also, if the stories are helping to build a positive community within the prison, like by inspiring other inmates or promoting positive values, the prison management might decide to give the prisoner extra time.