Great charge him and send him to jail if that report is accurate and they have the proof.
Both parties can be violent criminal scumbags, that's not mutually exclusive.
If the man on the floor who was kicked in the head violently assaulted someone prior to that and caused the damage alleged he should face the full weight of the law.
But that does not somehow make the actions of the police who have been caught on camera self defence or reasonable force.
The kick was absolutely 100% letting him have it out of anger, potentially in revenge
It did nothing to secure the area or make things safer. Talk of grenades or grabbing guns at that point is a nonsense, how did the kick go the head and stamp on the back guard against that danger in any way.
So both should be facing criminal charges even if the claim of the police (for which we've seen no evidence yet) is accurate