Your argument is applicable against all incarceration
Does that mean you do not favor incarceration at all?
Of course crimes may be committed in prison. And as stewards of the system, it is our duty to limit them to the best of our ability. But realistically, crimes committed in prison are not nearly as much of a concern to me as crimes committed out of prison, since I am not in prison.
People in prison cannot harm me or my family. That's all I meant. This is a silly quibble.