Well, the justification - mind you, I don't agree, I'm just answering your (rhetorical?) question - is that speech can sway opinions, opinions can shape behavio

Well, the justification - mind you, I don't agree, I'm just answering your (rhetorical?) question - is that speech can sway opinions, opinions can shape behavior, and (the wrong sort of) behavior can lead to chaos, so it's best to nip the wrong sort of speech in the bud before it cascades into genocide. The problem with that sort of "slippery slope" thinking is that it always ends up slippery-slope-ing in the other direction: hate speech regulations designed to silence nazis calling for genocide are almost immediately applied to reasoned, principled, thoughtful people like Jordan Peterson whose conclusions are outside the mainstream.