If you reside and have your vehicle registered in New York State you will need to have your auto insurance in New York as well. NY requires the auto insurance for a NY resident to be issued by a company authorized to do business in NYS and licensed by the NYS Insurance Department.

Class 30 auto insurance in Massachusetts is for when you are using a vehicle for business use. In NY it states that if a passenger car is used to give rides for hire it should be registered as a taxi or livery but you say your car is not a livery so it appears your rides are not for hire.

If your insurance agent is saying that you fall into a loophole you should check with other insurance companies to see if they can help you with your needs. Beyond that you can check with the New York State Insurance Department to see if there is any business use insurance that you qualify for and if so what insurance companies handle that type of coverage.