She was forcibly removed because she would not comply with the officer’s lawful order to exit the vehicle on her own. If there is any question, it might be why he told her to get out of the vehicle.
However, doing so is a common procedure and the right of the police to order drivers and passengers out of vehicles during lawful traffic stops was affirmed by the SCOTUS in Pennsylvania vs Mimms.
The order for her to exit the vehicle was not legal. The order came at the end of the trooper’s lawful reason for the stop. At that point, there is no longer a need for detainment via custodial stop. The officer did not like her smoking which she is legally allows to smoke in her own car. There is no need or cause for her to exit the vehicle. SCOTUS has also ruled that police and hold you only long enough to execute the stop.