"Nonpunitive"? So does this mean that government can require any group of people it wants to register with the authorities?
Sounds like somebody's using child molesters as a tool for engaging in a different kind of "molestation".
What the people do with the information provided by this law can certainly be punitive.
And you're right. Do I also have the right to know if any of my neighbors have been convicted of burglary? Arson? Assault? Rape?
Where does it stop?
This is a surprise? Do you want to vote? Do you drive a car? Do you want to be able to buy ammunition? You have to register with authorities for all kinds of things already, most of which have nothing to do with your status as a felon/non-felon.
Not communists --- the U.S. Supreme Court has ruled (1060s - 1970s I think) that the Post Office could not require people to sign for mail from communist countries --- it might inhibit people.