Hmmm... I really wonder what the said tyrants did when they got into power? Oh that's right they imposed heavy restrictions on speech and all forms of media. And it's not like there was free speech before them, the Weimar republic tried banning them as well. It's almost like challenging ideas and defeating them on an intellectual level is far better than trying to supress them.
... Yeah but they didn't do that before they were in power. They abused misinformation to get to a position to then lock it down. That's indeed what I'm saying.n I'm not disagreeing that they lock it down once in power.
Absolutist free speech would allow you to publicly plot the assassination of whomever you wanted to, or permit insider trading, etc.
Speech is a tool. It's utility and morality depends on the weilder of it.