I can see a thousand ways that could be misused in the aid of authoritarianism. Try speaking it in a German accent, perhaps with "vhere iz your mister Churchill?", and I'm sure you'll see the problem.
> akin to shouting fire in a crowded theater
That was the example given by Justice Oliver Wendell Holmes Jr for the clear and present danger test[1] in Schenk vs United States[2]:
> The ruling established that Congress has more latitude in limiting speech in times of war than in peacetime and set out the clear and present danger test, in which Justice Oliver Wendell Holmes Jr. indicated that the most stringent interpretations of the First Amendment would not protect a person who causes public panic by shouting “Fire!” in a theater when no fire exists.
I don't see how that test would apply to Trump, even in wartime.
[1] https://mtsu.edu/first-amendment/article/898/clear-and-prese...
[2] https://mtsu.edu/first-amendment/article/193/schenck-v-unite...
I think it's more than this. Trump's tweets have had significant real world consequences. Questioning the integrity of the US elections based on no real evidence eventually led to an insurrection at the US Capitol. When someone's speech is actively dangerous, it makes sense to block it, akin to shouting fire in a crowded theater.