According to one story that was referencing the cop’s arrest report, he was not arresting her at the time he cuffed her. He stated that he was cuffing her for officer safety because she was hostile and threatening. Cuffing does not always signify arrest. Both TX law and SCOTUS have agreed that an officer can cuff a person, that is not under arrest, for the purpose of officer safety. Once the interaction is concluded then the cop would remove the cuffs and let her go.
Unfortunately, she decided to fight the handcuffing so when she was asking about why she was under arrest, she may not of actually been under arrest at that time. This may have been her ignorance of the law. The cop may have only decided to arrest her once she decided to fight him.
Her actual arrest charge was for ‘assault of a public servant’. She was not arrested for resisting arrest or refusing to follow a lawful order or for a traffic violation.
Its the oldie but goodie "Why are you arresting me?" Because you are resisting arrest." "When did you start arresting me?" "When you resisted arrest."
Sometimes people that try and provoke police officers don't have a firm grasp on the law and then it backfires on them.
Here is another example of the news media and our president not supporting our police officers which causes people to give a cop an attitude.