Which are the two dictatorships you are thinking about?
Your proposed rule might be unpractical, since it would disallow the U.S. government from from saying anything about free speech for at least 30 more years (see [1] and [2]).
It's a sliver over a hundred years ago now, but Germany was also under a military dictatorship lead by Hindenburg and Ludendorff from 1916 through 1918.
Free speech was all but dead between 1914 and 1918 everywhere. Not saying Luddendorff wasn't defacto military dictator, he was, just pointing out that this had no additional negative impact on free speech during this time.
I was talking about the Nazi and the GDR regime. I am aware that US foreign policy is controversial, but never did the US murder people on a comparable scale.
Your proposed rule might be unpractical, since it would disallow the U.S. government from from saying anything about free speech for at least 30 more years (see [1] and [2]).
[1] https://en.wikipedia.org/wiki/1953_Iranian_coup_d%27%C3%A9ta...
[2] https://en.wikipedia.org/wiki/1954_Guatemalan_coup_d%27%C3%A...