Property owners who are legally defending themselves and their property from rioters would only be using a firearm on a trespasser, and so it is up to the individuals who wish to risk such a solution to their illegal behavior.
Looting, rioting is not an activity any thinking person wants to perform and that leaves those who assume the risks, and reap the consequences. It is a lot of hassle to shoot someone, especially if they are left only wounded to sue you forever for support. Not something anyone should take lightly, especially rioters, looters, and generally agitators or those following such creeps.
Hey, wont be any trouble, right, as Mr. Browns family is calling for calm, and we all know how much his 'friends' respect them and all, right? Will the the circus the family has desired, from their first fund raising trip, to their UN Geneva trip... good for TV ratings, right?