Say what you will about what is or is not legal, but this guy brought this upon himself. Any time some handles a firearm, unholstered, in a densely populated place, you can exepect things like this to happen.
As for the title of this thread, I agree. I won't knock anyone who chooses to open carry, but of all the stories I've ever heard about responsible carriers being harassed by police, not one of them was carrying concealed. Each mode has its advantages and disadvantages, but concealed gets my vote every time for that reason alone.