While he remained in prison, yes. Certainly failing to imprison him earlier didnt work, did it

Nothing was done though. You make it sound like the only two choices were to jail him or do nothing.

And talking about punishment completely misses the point. Sentencing needs to about risk management, not punishment.

Risk management would be to find him some treatment to overcome his childhood trauma.

Punishment by itself achieves nothing, offenders like this cannot be deterred. And sometimes incapacitation is all we have got

And sometimes we have other options but the cruel and sadistic public is always braying for blood and guts and hurting abused children as much as humanly possible.