Although this dealer sounds out of line, there are specific instances when its perfectly legal to have drivers lic and vehicles registered in different states. The most common is for owners of multiple homes who leave a spare vehicle in their out of state 2nd home.
My primary home and 8 of my 10 vehicles are in SD. But the spare pickup I leave at my NM winter ranch is not only allowed, but required to be registered and insured in NM. The Jeep I leave in the garage of my summer home in the Co mountains is required to be registered & insured in Co. I have no issues when stopped by LEO and show my SD license while driving my NM or CO registered vehicles. When registering, after telling them my primary home & drivers lic were SD,I did have to show both NM and CO, documents proving my home ownership & local utility bills. But the registration shows my SD address, since I don't get mail in NM or CO.
There are 1000's of NY'ers with vehicles registered In Fl and left at their part time Fl homes. Likewise here in CO, I see 1000's of Texans with CO registered vehicles that are kept here at their summer homes.