Why? Of course, it would depend on the criminals. You wouldn't want a convicted murderer, or a three-time violent felon to be out there, but some guy doing a year for smoking pot, or a DUI conviction, wouldn't be a likely threat to escape, and the benefits of having time trimmed off their sentence and/or extra privileges in the prison, would be a great incentive.
I think these jobs would have been in demand, if only because of the job security, at least before the anti-union laws were passed. I'd be surprised if there weren't people lined up waiting for an opening.I very much doubt if ordinary workers would miss out as the jobs are most probably available because no one will do them.