"I think we have to treat criminals more as victims of their circumstances. It doesn't make sense to harm or handicap them further. They need a well-guarded, natural location, an island where they either learn to establish order and farm or they eat one another."

I love this idea, I agree it's far better to allow down-syndrome to eat each other on "Scum island" rather than harm or handicap them further. Much, much better. ;-)

But.
Isn't humanity about compassion and, sometimes, coercion? Why do we bar young children from eating each other then?
We will always be bound to exert some coercion, one way or another.
I would like to offer coercion a second chance by sending blood and related criminals on a floating, offshore, self-sufficient, self-funded, distant factory designed solely to remove plastic and pollutants from the ocean and making money out of that by suing polluters, reselling recovered resources, etc... There, they will be given the option to benefit some monitoring and protection, as a paid service. Otherwise, they would organize and protect themselves. In both cases, the tax payer would have nothing to pay.