I guess my response would stand on what the regulations are regarding acceptable behavior in a National Park location. I do believe there are regulations against commercial advertising within park boundaries. And to stretch a bit, if you are protesting, you are advertising your point of view.
I'm not sure how the Park Police drew a connection between dancing and demonstration. Although those two should have been arrested by the "dance police".
I find it annoying that any group of people thinks it is okay for them to inconvenience everyone around them so that they can press their agenda, generally on people that really could care less about what they have to say. But that is what the freedom of speech is all about.
To not stand against injustice is to stand for it.
Don't confuse my personality and my attitude.
My personality is who I am, my attitude depends on who you are.