RE: Seized engine
Being it was in the air at the time, I doubt it ingested something.
More than likely the ring caught a port edge and broke.
This is common if there isn't enough radius on the top and bottom edges of the ports after honing or port-work.
It can happen too if there isn't enough ring gap and on a lean run the ring will expand into the port.
If the motor was stock, I'd send it in for warranty work.
If you're on you're own, buy a new piston & ring and if the jug doesn't have any deep gouges, hone it and it will run just fine.
Definitely put some more relief on the port edges and check the ring gap to avoid this again.
Kirk