Here's a thought...don't go to a private speaking event and try to suppress everyone's First Amendment rights. Doesn't mean anyone deserves to get punched, it means when you try to crush people's rights some may get angry and lash out with a fist. So the answer is, let the candidate and his followers freely exercise their constitutional right to free speech...and then there's not even the possibility of violence. The fault rests with those attempting to suppress people's rights (anti-Trump radicals sent by moveon and other rad groups) and yes, with whoever lashes out with violence because they are angry over having their rights taken away...it absolutely does not rest with Donald Trump or any other of his supporters.
Are you serious? You do know that First Amendment rights can only be suppressed by the government, don't you? The First Amendment prohibitions don't apply to private individuals. And two or three individuals in a sea of Trump supporters are not going to be preventing anyone from having their say. And finally, these two were already on the way out, and not voluntarily. The fault lies entirely with the Trump supporters, not with the protestors. I feel sorry for the Trump supporter who got arrested; he probably started out the day in a nice comfortable house he earned with his own hard work, and is going to end up in a dank ugly holding cell, but that is entirely his fault.