If I did that to her, I’d be facing more than one felony. Doing so under color of authority should be an aggravating, not a mitigating factor.
The mitigating factor is that she was arrestable for an offense, at least in Texas (driving with a suspended license.) Once an actor is under arrest, there are grey areas of conduct by the officer, depending on all factors perceived by an officer. I'm not saying that this wasn't a serious abuse of authority, but even as a civilian, this wouldn't have been a felony offense. Let's not make it worse than it appeared; it was indeed alarming and humiliating, but the woman wasn't harmed.