Staying out of the whole 'who was at fault' debate, I'll just say this: CARNZ is right. If you starve a 2-stroke engine of oil, you can forget about replacing JUST the rings. There won't be much piston ring left by the time the engine comes to a stop.
When you scorch a 2-stroke due to a lack of oil, it will either seized up solid, or the rings will have melted into the piston on the exhaust side, and you'll have metal transfer to the cylinder wall around the exhaust port. (Score marks). If this happened to the OP's stepson's Blaster, it would be obvious. The engine would either be locked up tight, or it would kick over 'dryly' with the burnt piston/ring mess dragging the cylinder wall.
Point is, if it is still running and the engine isn't hard to start cold, it survived and you got lucky. Like others have said, certain 2-stroke oils actually call for a leaner mix and they are designed to run this way. AMSOIL Saber is a 100:1 oil straight from the bottle, and at least one member on here has had luck racing with it (I don't remember his name, but he hasn't been on in awhile.) I run AMSOIL Interceptor at the recommended 50:1 ratio in my Blaster and have had nothing but the best results. My engine runs fine, throttle response is snappier, and I have a bit more usable power than when running pre-mix at 32:1. Bottom line: Follow the directions on the oil bottle.