I would have kicked his ass, too. Nobody hits a lady whie B-chan is around.
That being said: anybody intervening to stop this guy would have paid dearly for their actions. There are good cops and bad cops, but in the end Blue looks out for Blue. Cop pride will not tolerate a "civilian" laying hands upon a cop. Anybody who tried to take this guy down would have found himself looking down the barrel of the entire Chicago PD. Touch a cop, even in a good cause, and you're asking for harassment, intimidation, maybe a good old-fashoned Rodney King-style ass-kicking — after a routine traffic stop, say ("He grabbed for my gun, Your Honor!")
I'd have done it anyway, though, same as the rest of us.
Yes, I know.
I have had many LEO acquaintances (only one who was more like a real friend). I have little respect for local law enforcement.