I disagree. The cut should support the program itself and then further offset taxpayer expenses related to housing, feeding, and caring for the prisoner. I could even see a case for taking it as a way of ensuring it was saved and returned at release.
It's even worse with the privatised prison system that the US has.
This is a state by state thing. FWIW in this case, ME doesn't have private prisons. I don't bring this up to imply everything related to their cut is on the up and up, however, I believe Maine is very much incentivized to make this a useful program in terms of keeping people from returning to jail (as opposed to squeezing every dollar from the prisoners).
Fuck no! Lowering the cost of keeping people in prison would make it even easier for the government to lock people up for smaller crimes and with bigger sentences. It's even worse with the privatised prison system that the US has. They already know the "market price" (what the government is willing to spend) so adding "free money" into the equation just makes it easier for them to raise prices and end up pocketing even more money than they already do.
Framing it as offsetting the cost would also make it very easy to increase the cut, bit by bit, until it gets to a truly unreasonable level. And since the person is already in prison and we have to pay for them no matter what, why would they choose to work if the deal is so bad?