I disagree. The framers would have kept a person in prison if they were not fit to be set free in civil society. If they were fit to be free, they were also fit to keep and bear arms.
Too bad we can't return to the framers way of thinking and the individual liberty they enjoyed.
Who says the framers thought that way? It's nothing but an urban myth that they intended on keeping everybody who wasn't fit to be armed in a prison. WHAT prisons? The ones every jurisdiction was building and staffing with the combined funds from the colossal federal, state, and local income taxes that were being collected from citizens of the late 18th century United States?
They had common sense back then, and everybody understood that convicted criminals and insane/retarded people were not to be given the same freedoms as normal people.