it varies by jurisdiction, but yes… theoretically an adult propositioning a 12 year old online is illegal. The Dateline: To Catch a Predator stings were based on that.

He’s probably “legally” fine since he had the parents’ permission. But morally its pretty bad, and as the links I left point out, the damage from the trauma that the girls received is probably REALLY harmful and likely to make them counteract in more self-destructive behavior.