EMT's don't always run sirens and lights in emergencies. It's obvious this amublance wasn't trying to set any land speed records and wasn't passing through an intersection that would have warranted them either. As soon as the EMTs said they had a patient in the back the conversation should have been over. Nothing the EMT did warranted the officers response. It's not assault to gesture at or even touch an officer. Assault is defined by the intent, there's no way that EMT moved in a way that indicates he was trying to cause harm. If anything that officer should be charged with a felony assault against the EMT who was medical services personel who was acting in the performance of his duties when the cop got out extremely aggressive, yelling and putting his finger in the EMTs face.