It made me think a bit.
Look, protest is a First Amendment right, and the First Amendment only prohibits governmental silencing of anybody.
So the constitutional rights of Donald Trump and his supporters were not violated. Indeed, it was Trump himself that cancelled the rally.
But we have a culture of free speech in this nation that is deeply embedded in our politics, and goes beyond the technical legal rules. And I do not support the shutting down of anybody's rally and the silencing of anybody's speech. Justice Louis Brandeis wrote in Whitney v. California:
Those who won our independence believed that the final end of the State was to make men free to develop their faculties, and that, in its government, the deliberative forces should prevail over the arbitrary. They valued liberty both as an end, and as a means. They believed liberty to be the secret of happiness, and courage to be the secret of liberty. They believed that freedom to think as you will and to speak as you think are means indispensable to the discovery and spread of political truth; that, without free speech and assembly, discussion would be futile; that, with them, discussion affords ordinarily adequate protection against the dissemination of noxious doctrine; that the greatest menace to freedom is an inert people; that public discussion is a political duty, and that this should be a fundamental principle of the American government. [n2] They recognized the risks to which all human institutions are subject. But they knew that order cannot be secured merely through fear of punishment for its infraction; that it is hazardous to discourage thought, hope and imagination; that fear breeds repression; that repression breeds hate; that hate menaces stable government; that the path of safety lies in the opportunity to discuss freely supposed grievances and proposed remedies, and that the fitting remedy for evil counsels is good ones. Believing in the power of reason as applied through public discussion, they eschewed silence [p376] coerced by law -- the argument of force in its worst form. Recognizing the occasional tyrannies of governing majorities, they amended the Constitution so that free speech and assembly should be guaranteed.Now, the legal ruling for which Brandeis (and Holmes, who joined this opinion) was contending does not apply to this situation, as only private actors were involved.
Fear of serious injury cannot alone justify suppression of free speech and assembly. Men feared witches and burnt women. It is the function of speech to free men from the bondage of irrational fears. To justify suppression of free speech, there must be reasonable ground to fear that serious evil will result if free speech is practiced. There must be reasonable ground to believe that the danger apprehended is imminent. There must be reasonable ground to believe that the evil to be prevented is a serious one. Every denunciation of existing law tends in some measure to increase the probability that there will be violation of it. [n3] Condonation of a breach enhances the probability. Expressions of approval add to the probability. Propagation of the criminal state of mind by teaching syndicalism increases it. Advocacy of law-breaking heightens it still further. But even advocacy of violation, however reprehensible morally, is not a justification for denying free speech where the advocacy falls short of incitement and there is nothing to indicate that the advocacy would be immediately acted on. The wide difference between advocacy and incitement, between preparation and attempt, between assembling and conspiracy, must be borne in mind.
But there are two very good reasons not to approve of deliberate efforts to shut down the rally, as NBC reports this was just such am effort (see here). The pragmatic one is that it legitimate a reciprocal efforts, and allows the silenced party to claim free speech martyrdom.
But the principled one is just that alluded to by Justice Barndeis in his masterful concurrence in Whitney, above quoted: It's just not how a democratic republic functions, if it's to function at all. It's messy, with protests, and speech both vying to be heard, but silencing even the worst speaker is itself a danger to deliberative democracy. It erodes the culture of free debate that is, God knows, far from perfect, but the best thing we've got.
When I was a college student, I was invited to participate in a debate between a member of Pax Christi, arguing that our college should ban the CIA from recruiting on campus, and a representative of our ROTC, defending the Agency. I had more politically in common with the Pax Christi representative, and we joined in criticizing much of the misconduct then coming to light. (This was the mid-80s, so there was a fair amount). So I ended up irritating both sides pretty severely, by arguing in defense of the right for those I firmly believed to be wrong to be heard.
I still think I was right then, and that the same lesson pertains today. Protest by all means--but shutting it down is shutting down the debate by which We the People decide our fates. That's inherently dangerous, and wrong.