Here’s a novel idea: How about keeping them in jail?
But check the archives and you'll see that "sex offenders" also include
a 16 year old boy having sex with a 15 1/2 year old girl
a teacher who turns on a computer in class that had previously been infected with porn spam by another user
a man "exposing himself" by taking a leak in what he thought was a deserted alley.
So I want to know exactly what the crime is before making blanket statements.