This is lunacy, plain and simple.
Fighting fires is one thing; coming face to face with the hardcore criminal/lowlife elements of society is quite another. The prison officer job is a specialist one requiring a mindset that will be quite alien to most in the military. The only time the military bumps against these elements of a society is when they are war with them and they see them at the end of a barrel of a gun.
Many moons ago I lived with a female CID officer. She was always disparaging about the Military Police..."who'd want to police a disciplined, highly ordered, law abiding section of society, what's the point?"
Her comments resonate now. This is not work for the military...if needs must, get the police to do it. Pull them off traffic duties for a month or so....there will be more than enough.