He was 16. It was a different former page who recieved IMs when he was 17 and 18.
That's the point. The kid who received the benign emails was 16. The guy who received the explicit IMs was 18. But the media made it sound like the explicit messages went to minors. They even went so far as to redact the IMs to hide the identity of the 18 year old, leading one to believe that they did so because he was a minor.
Unfortunately for them, they messed up the redaction on one of them, and their fraud was uncovered. Yet there is hardly a murmur about their ploy.