Domain, you may be correct. The policy changed close to five years ago, so it would depend upon either the warranty certificate that came with the unit or the serial number of the unit to make that determination. If the customer has a copy of the warranty that came with the product that states an extended sealed system warranty, then they must honor it. I worked for the International division and we had different warranty policies, so I am not completely up-to-speed on the Domestic division's warranty changes. I know that when we heard about those changes, we disagreed completely with them. I argued that if the company can't have enough faith to back up a product such as a major appliance better than a one year only warranty, how can you expect a consumer to have confidence in your product? But industry trends prevailed . . .
As for the technical article about compressor replacement, that is true due to the moisture issue as stated. I don't think it applies in this case because the unit still had some cooling capacity and thus was most likely not run void of refrigerant. However, as AJ pointed out, there must be a leak somewhere that should be located and repaired. I've run across short charged units in the field that didn't have leaks, but they wouldn't have operated satisfactorily for five years. That would have been noticed immediately following installation and first operation. In any case, sealed system work is costly and may not be worthwhile in this situation.