I'm going to try and nail down some of these objections if I can. Forgive me (and correct me) if I've misrepresented your argument.

Objection 1: Not everyone in the database is going to re-offend.
Answer: Of course not, but there's currently no way to predict who will and who won't. (Those who have sought treatment are less likely to re-offend than those who haven't, but there are still plenty of "treated" folks out there who do.)

Objection 2: This database screws up the lives of people who truly are rehabilitated.
Answer: There are examples here and there of people acting out against sexual offenders, but I haven't seen any evidence that this database contributes to this violence. This argument is a bit like saying that we shouldn't publish kids' pictures in the newspaper when they win a spelling bee (or whatever) because a pedophile could use that information to target them.

Objection 3: This database lulls people into a false sense of security.
Answer: How? Is there any evidence for this? Has anyone ever even heard anyone say anything like, "Now my kids are safe, because this database tells me everyone who could hurt them and now I can keep them away"? I just don't believe that most people think that way, and I haven't seen any evidence to think otherwise.