I think so. Recently in Snohomish, WA, there was a protest planned shortly after the ones in Seattle turned into violent riots. The local folks were out on the street armed. One of them spoke to the leaders of the protest and basically said 'You're welcome to protest, but there will be no property destruction, no grafitti, and no littering'. One of the protesters handed him a Black Lives Matter sign. He took it, and everyone marched peacefully and went home.
It's always a good idea to talk to your neighbors, even if they suck. I think it's particularly important in this situation. You don't want JoeBob spraying rounds from his house into yours. Going to talk to the leaders/instigators will give you a good idea of what might be coming. At any rate, informing them that there will be armed citizens can possibly avoid tension later if they see people with ARs standing about. This isn't always possible of course, these things don't always follow planned routes, but sometimes they do.
Arson's not just a possibility, it's what's going to happen if things go south. The people that instigate/incite these things train for it. They have incendiary devices ready. They also have window breakers and other fun things made up. They've had a lot of May Days in Seattle to get good at this. Here's a few things I would do.
1. Have sprinklers going in all parts of your yard. The strong jet kind that go back and forth. Have them wetting your house at the back swing and going about 30 degrees forward on the front swing. People have an odd repulsion to getting wet. Wet houses are harder to burn. It won't stop a determined arson attempt, but if someone else's house is burning it can save yours from drifting embers.
2. Talk with your neighbors and find out who's ready to defend themselves/what their plan is. You might be willing to run, but what about the 85 year old lady that lives across the street from you and won't leave her 9 cats? Are you going to stand by while her house is broken into and vandalized? Have a plan before you get mad and do something anyways.
3. Talk with local LE/FD if possible and find out what they are dealing with in your area and if they're going to be able to do anything for you. I don't want to be out there armed with a bunch of stressed, sleep deprived tense cops while they come to that old lady across the streets house, but I don't want to abandon her if there's no help coming for her either.
I don't have any comments on the legal side of things.