This came up on a law enforcement subreddit. Riot police training is that the front line always keeps moving in order to provide a security barrier, the medics behind them will attend to anybody injured. In this case the medic was national guard. Supposedly it took 18 seconds between the time the man fell and the time the medic reached him.
So the initial shove was pretty horrific, but the line movement at least has a plausible explanation.