These types of internet stings have been around for years. Allowing the perp to believe he's convinced you to let him...uh...meet with you is in effect catching him in the act. He HAS a defense lawyer...I'd say he pleaded guilty to a lesser charge in order to avoid publicity.
HOWEVER, he had been caught TWICE when procedings proceded. The firing of the assistant DA for "breaking procedure" in this type of case, combined with the DA's admission that sealing the records of sex offenders is highly irregular only makes it seems as though a guilty perp was caught, and big time strings were pulled to hush it up.
It IS irregular: there are LAWS on the books to protect neighborhood children from repeat offenders...and if Ritter had gotten caught a THIRD time, WITH the record sealed...he would have had to be tried as a first time offender, if NY State law works like that of most states.