Harassed by a driver and the police did nothing

I am Thai, and my daughter is half Thai, half caucasian. We got Chinese takeout today in South Carolina and we walked out to our car. A white Honda Passport started to back up across the parking lot, so I motioned my daughter over as close to the cars on the opposite side as possible. He would not have hit us unless he planned on hitting the cars, too. He rolled down his window and called us g-dd—n motherf—ing ch-nks and b-tches and to get the f-ck out of his way. He kept yelling racial slurs. As he drove off, I flipped him off. That got him so angry that he pulled up on my daughter's side of the car, made more racial slurs, and threatened to beat our motherf—ing ch—k -sses. He then pulled in front of us (we pulled through the space when we parked) and opened his door as if he was going to get out of his car (he didn't) but he just yelled some more ... but my dashcam got his face, his car, make and model. I waited in my parking spot for a few seconds before taking off because I wanted to see if he planned to follow us out of the parking. In the video, you see him pulling around, but I got out of the parking lot before he did. I called the police, and they said that racial slurs and threats of violence are protected under the First Amendment so there is nothing they can do. Of course, I could have exercised MY First Amendment rights, also, but we would be violently beaten, if not dead. I will not take this passively. My daughter is 17, and she was terrified. I will not let this man win. I want to teach my daughter to stand up for herself and to fight.