"I recognize that in some situations it could hypothetically be the case that free speech leads to bad outcomes, in which case I'd be alright with restricting it. I think such cases would be fantastically rare..."
What about the "Werther Effect"? Journalism guidelines are drafted on the assumption that it is real, and browsing through PubMed suggests that the evidence is strong enough.
So, if imitative suicide is facilitated through art or media stimuli in predictable ways, isn't the empirical question as to whether there are "bad consequence of free speech" answered, with the reality being more prosaic than fantastically rare?
Unless you don't think suicide is a bad thing, I suppose.
ADS may be observed, most tragically, in the history of "facilitated communication."