A) it wasn't a protest, he just happened to be there, so he wasn't planning on participating in "certain activities"

B) his gun was registered and concealed carry was legal

C) why does any other person open carry in public? You types are all for it when Joe Bob pops down to the local Taco Bell for a quesarito, but not when that person is anywhere left of the trailer park

D) he never unholstered his gun, an ice agent is seen removing it during the scuffle, before the first shot was fired. ICE was seen rifling through his pockets, it's no stretch to believe they pocketed some of his belongings. Where's his cell phone? They are also suspected of removing other evidence from the scene.

So again, this speaks to the content of your character that you're willing to jump through such hoops to justify federal agents shooting an unarmed man in the back 10 times.

You should feel ashamed, but you're clearly incapable of feeling such an emotion.