It was an accident. He never meant to hurt anyone. Either the police didn't block off the road or Antifa had no right to be there. Either way, automobile traffic was still flowing into that intersection.
Antifa was out with baseball bats, Coke cans filled with cement, aerosol cans used as flamethrowers, and tear gas, as reported by the police and journalists on the scene. When his car got hit with rocks, he panicked and accelerated. He also tried to brake, but he crashed into people. Rather than letting Antifa beat him with bats, he reversed his car, got to safety, then surrendered peacefully to the cops. The cops who were not at the scene of Antifa's riot.
The people who actual deserve blame:
>the Mayor of Charlottesville, for ordering the police to stand down
>the Charlottesville police for either not securing the Antifa riot or for abandoning their duty when faced with Antifa's mob violence. They also deserve blame for funneling the ralleygoers between a gauntlet of Antifa, which heightened the tensions
>Antifa for possibly not having a legal right to organize, and definitely for carrying weapons to their riot