Logistics may play a part. If the engine is in Idaho , JGM is in the north end of Southern California which is close to a thousand mile separation. If the issue was simple like a gasket or PCV , it would make sense to fix that where it is. However what my trained eye saw with the bore - o - scope pictures is NOT a "field fix". I agree with you Bob , in that if "I" were the builder , I would want to do the tear down. Not because additional damage could happen , but because "clues" could be lost in the process by someone not seeing them or knowing what to look for. We can easily agree JGM did not "build" the engine with scratched up bores and it probably didn't smoke when it was on their dyno. "Something" has obviously changed.
Randy