He has the right to free speech too, does he not? Notice how its his speech you want to stop?
Yes, I notice, so let's look at one of his favorite sayings, the press is "the enemy of the people".
A free press has long been one of a democracy's principle vehicles for speaking truth to power.
And a president's words would be expected to carry more weight, on topics pertaining to the functioning of our democracy and government, by virtue of being chief executive of the federal government. They may not be weighty intrinsically, but by virtue of who he is, his words will carry weight.
Is it right, given those two premises, for a president to turn the phrase the news media is "the enemy of the people" into a mantra, by virtue of stating it repetitively? If I defended his right to say it, could I nonetheless say it's irresponsible for him to say it? Yes, my free speech gives me the right to call him irresponsible in this case. And, if it's irresponsible, given the function of a free press to speak truth to power in a democracy, then should he be saying it, to the point of being a mantra?
I believe he does damage to one of our most important democratic institutions by both saying it in the first place, and turning it into a political mantra in the second place. The behavior of his rally attendees toward the press in attendance at those rallies, would suggest they believe the press is their enemy. He did not create that belief, but he promotes it, and his words carry more weight then yours or mine.
So, yeah, it is his speech I want to stop. Because it's irresponsible to say it, and damaging to a democratic institution by saying it over and over, not because he does not have the freedom to say it.