I filmed that video. Lots of misinformation going around from news outlets.
The skater broke his ankle, tore his knee tendon, and sprained his fingers. The cop stepped into a zone in an effort to stop skaters as the parks vehicle was getting ready to leave. If he had dealt with the situation properly, he would have waited until there were no oncoming skaters and walked up the hill to direct them away from the corridor. Unfortunately, he decided to cause even more danger by blocking the area skaters were going through. He also put his weight into the collision. There is another video filmed from above that shows the cop intentionally stepping to his left to make contact with the skater.
The hill bomb event was unsanctioned and unpermitted. However, when it went down last year the police handled the situation much better by not attempting to knock skaters over.