This is all nonsense. Penal Code 400.00 says that you must notify the issuing authority within 10 days of moving. The law says NOTHING about the license becoming invalid, suspended, or revoked. According to the law, as long as you notify, your license is still good for life (unless you live in a county where it expires).
As far as adding pistols to the license after you move out. Good luck with that, I don't know if it has been done before or not.
Regardign residence, it is not defined by having a drivers license. If you have a dwelling in New York, that is a residence. There are plenty of people from out of state that have pistol licenses.
Remember back when rockland county had all permit holders addresses published in the paper, there were quite a few permit holders who lived in New Hampshire, New Jersey, and Connecticut. I doubt the person from New Hampshire had a business in Rockland county. It was probably a house or condo or something similar.