Correct. They used to do home-deliveries to satisfy this requirement.To add onto this, technically you are able to purchase cars in MA if you are from NH but you just can't take delivery of it in MA.
The work around most dealers in MA do for NH buyers is to have a dealer rep drive the car up to NH and do the paperwork (registering and etc at NH location like a Townhall). This prevents point of sale tax being paid to MA.
The issue and reason why Tesla doesn't do this is because they simply don't have the manpower. They don't have workers to drive the car from MA to NH and meet people at the Townhall to do all the necessary paperwork. It takes at least 1-1.5 hours of driving, 1 hour at least for paperwork if no line, and they need another driver/car to pick them up and go back to MA after.
Not sure why the service isn’t offered anymore since customers were paying for the transport.