Hmmm...so if you enter a bank with bank robbers and just "hang around" with them...are you guilty of bank robbery?
Yes you are
We’ll, this wasn’t a robbery, there were many people there that day, some to protest, some to riot, some just got caught up in all that was happening.
Doesn’t mean he was there to riot, we don’t see him rioting, no evidence he broke anything or assaulted anyone. He was just in the crowd that day and walked into a public building.
Now, to your robber analogy. If he planned with the robbers, and showed up with the robbers with the intention of robbing the bank, or assist the robbers in robbing the bank, then, yes, he would be culpable, but that is an entirely different scenario.
Let’s say the bank was holding a bake sale, and they ran out of macaroons waaay too early, and people got unruly, and started to riot, and during the riot they broke into the bank and ransacked the place, but Viking guy, who just showed up for the double fudge brownies saw what was happening and said “hmm, I’ll take a look around”, and walked in behind the people angry about not getting their macaroons, then nah, I’d say he wouldn’t be culpable.
At worst, I’d say that Viking guy could be charged with trespassing…but since it’s public property (the capitol) I’m not sure if that’s a valid charge.