Even if the accused HAD injured a LEO, there is absolutely NO lawful reason that a different LEO can beat the shit out of the perp.
LEOs are not the Judge, Jury, and Executioner. PERIOD!
This reminds me of the video of a different perp that ran from the cops, wrecked his car and was thrown from the vehicle into a ditch... unconscious. En masse, the cops came up to the unconscious man and beat the shit out of the seemingly-lifeless body.