Now, I'm torn. On the one hand, the guy's in prison. It's not vacation fun time, it's incarceration. I hesitate to say it is punishment, because while it may be that, it's not like he can learn his lesson and do better for the future. On the other hand...seriously? Four inmates decide to play D&D. Not standing around, pumping iron, facing off against each other, raping others in the sower, rioting in the mess hall...using their minds and imagination for a mental exercise.
"Competitive hostility, violence, escape behaviors"? Are they aware that this is a prison? This is what people who are held against their will DO. They get hostile, violent, and want to escape. It's animal nature. If all these guys want to do is hang out and slay dragons, rescue innocents, and valiantly conquer impossible odds with a sword and shield...let them. Which is a biggest issue, the toughs who want to fight and run their prison fiefdoms through violence and terror, the recidivists with a revolving door on their cells, or the geeks who relax quietly in a room, telling stories to each other of fantasy worlds?
I admit, it makes me want to start a Play-By-Mail game for them.