So what's the age limit you believe should exempt people from prison?
Depending on their overall state of health, not beyond 60. A rehabilitation unit would be better served as a correctional building for those prisoners/offenders whose mental/ physical health is impaired rather than a prison cell and everything that goes with it.
Old age is horrendous if you haven't got good health and prison isn't the place to improve it. To start with those who commit crime be it petty or heinous already suffer mental health issues or they wouldn't commit crime would they ? We all hopefully know right from wrong, but these people don't it's as simple as that and prison is no place to learn.
The whole prison system needs overhauling anyway, but left to who's in charge

I can't see that happening any time soon if Birmingham's anything to go by.