Just because the property is public doesn’t mean the public can do whatever they want in it
Yes, but what those people were doing was exercising their first amendment rights. It's not like they were going around punching people, or shouting "Fire!". And considering that they were there attending a town hall, it's really hard to make the case that they were loitering.
People who are interrupting whatever is going on can definitely be removed from the proceedings.
I don't know that that's true, legally speaking. I am, however, ignorant of a great many things, and this is definitely one area in which I feel a profound deficiency. But just because people routinely get abused in this way by the police doesn't necessarily imply that it is legal for them to do so. As you point out in your next sentence, cops use violence with impunity, and our justice system tends to look the other way when they do.
Yeah, that was more my point with my initial post. I understand escorting someone from the premises if they are causing a huge scene, but these cops violently wrestled these people out of there, even employing a potentially lethal weapon on two occasions. Many people have died over the years from being tased, and so to see it being used so wantonly is incredibly disturbing.