Why should the taxpayers be burdened by the results of his bad decisions?
/me takes off hat
Someone can both work towards rehabilitation and pay their 'debt to society'. If they earn over what it costs to house them in a Maine prison then, by all means, let them keep the excess earnings. If they earn $100k/year and the state pays them $1.35/hr then there are deeper institutional issues around prison labor exploitation which should be addressed.
I used to have an uncle who was constantly in and out of prison over drug-related issues and he would do all sorts of work programs just to break up the monotony. Ironically, none of these rehabilitation efforts did any good and what finally 'set him straight' was the Three Strikes Law.