A1 driving to the basket on a fast break. B2 is chasing from behind. A1 two step stops and B2 continues and snaps the rim before A1 attempted any type of shot. My partner assessed a technical foul. Did he get it right?

Yes. NF 10-3-5. It is a player technical foul to grasp either basket during the time of the officials' jurisdiction, including during the game unless it is to prevent injury.