Sure there will always be some moral hazards around but this sounds like the human nature argument of capitalism, if there are moral hazards you can identify in specific parts of a system, do you either just discard that observation as inevitable or good enough, or do you look for ways to minimize the dangers there?

Just sounds like you're arguing with someone who is concerned over the morality of a revolution as a whole, instead of what the person actually said which is that specifically giving risky and dangerous jobs to criminals risks introducing an incentive to find more criminals for dangerous positions when spots are open(and, I would add, comes off as a kind of passive retributive justice, where instead of directly punishing a criminal you place them in a position where they are more likely to be "punished" by circumstance).