> What I’m objecting to is the imposition of the “no unsupervised time with your children” rule, which, to my mind, is a punishment just as much as a precaution.

Which is another way of saying that it is just as much a precaution as it is a punishment.

CPS responsibilities are to the children and their safety. The police & courts deal with the parents, collect any evidence, mete out any punishment, etc.