>> In a year's time, he'd be "legal" anyway. Couldn't our American pal have waited for that?

More precisely, he would be legal in less than a year's time. Although in the New York the age of consent is 17, so the web offence might still have stood, even if he had waited a year.

It would be interesting to know if he was aware other the teenager's age (it's a bit difficult to check ID over a webcam).