I would suggest that the engine gets stripped as if there was filings or cutting that came off they have likely damaged the engine. As the oil unit is one chamber - ie flywheel,gearbox, sleeve, sump. If there are filing then they could even have gone up the sleeve. You may have gotten away lucky but talking from experience, the filing got all over the place on my bike causing severe damages to the entire engine except the topend. Stripping the engine costing a gasket set could be much cheaper in the long run.