If you want to move on to covering something besides high school kids, you'll have to learn how to be confident enough to write stories without soliciting advice on a message board.
Is this a state where private schools and public schools compete in separate high school associations?
I guess you have school choice where you work... That's not possible in my coverage area, since the kid's required to go to the local high school unless there are specific extenuating circumstances like attending one of the magnet academies. I had a kid transfer from a private school to public in the middle of his senior year, after football season and before track. He also moved in with his sister so he could attend this particular public school after living with his mom (maybe 15 miles away) for the prior three years. The kid was straightforward about the reasons for his switch -- better competition because he realized he could maybe get college money for track -- but I still wonder if there's more to the story neither school nor family was willing to admit publicly. The timing is just that odd.
This sort of "recruiting" happens quite often. Sometimes it's just a matter of wanting to play for coach Larry. That's usually the official party line. Other times, there is money changing hands under the table. Either way, it's fine to talk to the kid and get his perspective.
Around here we've had a slew of kids transfer without moving. We had one kid say he transfered so he would get playing time without having to sit behind a player he felt he was better than. Here as long as the parents are willing to pay tuition to the "out-of-town" school district, it's OK. They just have to sit for a certain number of contests before being eligible. Actually one of them ran indoor track so he'd have to sit through those and not get stuck sitting during baseball season.
Don't shy away from talking to the student-athlete himself in this sort of situation. He's made himself a newsworthy figure. Go through the proper channels, sure. Check with the parents. But the kid remains the central character in the story.