The problem I see it is the definition of a sexual offender.

Let's say I go to a party, meet a girl. We like each other, we sleep together. She gave me the impression she was 18 when, oh shit. She was 15. Her parents hit the roof and have me charged. Hey presto, I'm now one of those 700 "sex predators".

So, unless you can remove every guy who was stitched up in a similar situation (and yeah, it happens), those numbers don't do anybody any service.