I think hes an employee at a major watch repair company in China, yes thats a thing in China, there are many watchmaking schools and large companies that have factories dedicated to repair and modifying.

A relative of mine, with connections to China and deals in gen pieces says that a fun fact is that alot of his clients that are insanely rich, and are watch fanatics, hire their own watchmakers so that they dont have to wait the 3 to 7 months you have to wait when u hand it back over to the AD to have them repaired.

There was once a story where one of his customer's Grand Complications Perpetual Minute Repeater had became faulty cause he accidentally wound the time backwards right after a date change, a part had broken inside and was loose. He handed it to his private watchmaker and it was fixed within a week.