He's scored another job in another province - one where these new rules are not fully
enforced

I hope that he is able to "score" a new FEC and Residency permit. His passport number is in the FT database that each province Immigration department and Chinese Embassy has access to and routinely reviews prior to issuing FECs or Z visas.

I do suspect that some provinces will be less rigorous on the criminal background and apostille documents for FTs that are already 'in house', but I would be surprised if the immigration officials overlook release documents of FTs new to the province because the 'scorned' school has the ability to report the midnight FT Run and it's easy for them to locate the runner since he will be once again added to the FEC database as now working for the new institution.

Additionally, if the visa documents he fills out are erroneous (they lack the prior employer), this falsification qualifies him for deportation.