Sorry, but even though i would never do this type of thing with a flag they can do whatever the hell they want with it. Burn it and what not. It was the biker guys property since he bought it. It signified distress since in new mexico it seems cops can do whatever the hell they want and get away with it.
Furthermore, it was a protest. Regardless what they were protesting they can protest just like the KKK can. Don't see Marines like this trying to stomp the Nazi flags when the KKK fly's them out in Georgia.
Either way, anyone can protest however they like. Its a free country. Or so we think Lol