This will probably be unpopular, but...
What happens when one of the people the are "protecting" breaks a law and is subject to arrest. Are they going to try to stop the police? So then they step in with their over inflated sense of ability and it escalates.. Then, somehow a shot gets fired, which leads to 500 shots getting fired... Nice.
Seems to me if the people were being peaceful and strictly in accordance with the constitution there is no need for some mall ninjas decked out with their rifles.. PS.. That camo doesn't seem to be working very well. I still see him.
Your "what if" could happen regardless of people OC'ing rifles or CC'ing pistols, or knives or even rocks and bricks.
If people want to escalate violence, they will with whatever they have at hand, and people will probably die. The only difference is how many.
You also assume that a peaceful protest won't be forcefully broken up.
Should we just roll over and take it?