There's another video, slightly longer, which shows that the police stop after a few more seconds and attend to him. I think they were a bit shocked by severe consequences of the shove and uncertain for a moment (even though it was a predictable result of the heavy-handed approach that the police have been taking that somewhere something like this would happen).

What is absolutely not forgivable, though, is lying that he "tripped and fell" on the police report. And it's even more outrageous that dozens of officers are coming together to defend that egregious lie!