At a guess, the pilot did a Lear type-rating in the States, when he was issued that restricted Commercial. Then he probably went back to Mexico with the US paperwork and got the Lear type-rating transferred to his Mexican ATPL.
That would be a simple way of getting the Lear type-rating, is all, to save having to hunt up a Mexican TRTO that did Lear type-ratings. The pilot would then have been using his Mexican license from that point, to fly in Mexico, including on an N-registered aircraft. There would have been no point to keeping that American licence valid if that were the case.
For instance, I once flew an N-registered aircraft in Nigeria on my Nigerian license, since my American licence was out of validity for lack of both an FAA Flight Review and an FAA medical. That was perfectly legal, so long as I stayed within Nigerian airspace, as I did. I would only have needed a valid American licence outside of Nigerian airspace.
Assuming that I had got something badly wrong, then our amateur accident investigators could have gone to the FAA website (faa.gov), looked me up and discovered that my American licence was out of validity and thought "Ah-hah!" that I was flying without a valid licence. Take things a step further and understand that one doesn't necessarily need to meet FAA standards to fly an N-registered aircraft legally.