I doubt that the Engineers from AMTRAK get to drive the freight engines. Railroads have to sign their Engineers out on locomotives. If they don't adhere to procedure do you think insurance companies will pay up in case of accident? The locomotives belongs to the host rr and while it is towing an AMTRAK train, the freight lines just don't let anyone drive it. Can you imagine a United Airlines pilot 'being shown the controls' of a different aircraft on British Airways and being allowed to fly it? The same day? Even with rail it takes a full day or two to learn the equipment. With airlines it is 90 days. Plus both require an assessor to 'pass them out' to make sure that they can drive the thing, whether it be a 747 or AC4400 or whatever it is. The newer high tech stuff is more involved. That is why I can't believe that.
Locomotives need PIN codes now issued by the company for the engineer. If the code is not entered the locomotive is not able to be driven. Better get advice from a REAL engineer to see how much is correct since I am going from experience. But Railroads are VERY sensitive about letting ANYONE touch their equipment. Serious!