what do you mean by blocked? people standing in the road? vehicles across the road? are they an actual threat, charging you? do they have weapons? if all they are is "pedestrians", of course you can't hit them. If they are attacking, of course you can shoot them. It's the in between stuff that's sticky. I can tell you that if my wife and kid are present, things will turn deadly a lot faster than they would if I was a long.
With protestors... Honestly if they are blocking the road being stupid, hammer the horn and slowly roll. The majority of people will get out of the way especially if the horn is EXTREMELY loud. I think it's about time to upgrade to a couple air horns in the near future with all the protests that have been popping up.