the cop did nothing wrong
but he is white and the attackers are minorities
so he’ll probably get fired and or jailed, because that’s how things work in liberal run places these days.
Pretty much that's the bottom line.
California Law gives Police Officers a few more powers than are afforded private citizens, among them is the power to physically arrest juveniles and persons committing assault (verbal threat of violence), so the cop was not out of line in the original physical handling of the kid.