You can't keep prisoners in solitary indefinitely - they have to be let out occasionally for things recreation (even if it's inside an enclosed "yard"), showers, etc. To do so is considered cruel and unusual.

The warden isn't talking about just violence against other prisoners. He's talking about prisoners attacking the guards, who are the authority figure who took the TVs away. These guys are on death row, with no hope of ever being released. If they kill a few guards, what's the punishment? Are you going to execute them twice? They have absolutely nothing to lose.

There needs to be something to occupy the prisoners time, or else they just have more idle time to stew and come with new ways to cause mayhem and violence within their little world.

This Republican show of being "tough on crime" is going to get a bunch of guards hurt and/or killed.