I support the use of force via a doctrine of using minimum force necessary to protect first lives, then property.
If rioters and or looters were threatening bystanders, then yes force may be necessary. If they were threatening to destroy property, it depends on the immediacy of the threat. If they were spray painting and maybe breaking windows, one level of force is acceptable. If they are holding malt liquor bottles with gas in them, that may require a much larger use of force. Fire in particular because you never know who might be in a building.
My perspective is that of someone who was born in the late 60's and was too young for that round of race riots (yes, race riots, not just protests) and lived through another wave in the 70's when I didn't know if my dad was going to come home, because he was there defending the family business downtown (we lived in an east coast city). So I don't have soft spot for looters, vandals, or others of the ilk. I'm liberal, but only up to a point.
When there are thousands of people it's often hard to judge what is acceptable appropriate force. I'll tell you what isn't appropriate: "Do you support the shooting of a protester with a rubber bullet who has climbed on top of a cop car?" Hell no. The car isn't worth the potential life lost. I don't equate a car with a life, nor do I equate it with a business. Also the consequences of using life threatening force extend beyond the here and now: it may precipitate a much larger reaction.
Again, these are two very different things. And I'm not naive. I was in grad school in California during the Rodney King episode. I actually talked a bunch of folks (mix of black and hispanic, a few whites and asians) from going down to LA. When it was starting they had all sorts of ideas about going down there and sticking it to the man, and I talked with them for hours over the course of an afternoon with a couple of other like minded people. They decided not to go down there and thanked me a week later.
We all get to make our decisions. It's a free country, particularly if you're white.