Throwing up our hands because "censorship bad!" is sick and wrong.
This is exactly what conservatives said in response to people promoting liberal ideas. Violent left-wing events in the 1970s (e.g. courthouse shootings) could easily have been used as a pretext for massive speech suppression. 9/11 and cries about the radicalization of Muslims through jihadist materials online could have been used the same way. Luckily none of that happened.
Good and wise people don't bring knives to gunfights.
And that is key.
PREEMPTIVE censorship is always a mistake because it only relies on power ideologies.
Their entire goal is to create a society where their gut opinions are just as good as knowledge from experts, because experts hurt their feelings (e.g. the Conservative reaction to the 1619 Project: https://en.wikipedia.org/wiki/1776_Commission).
Which is kind of a weird whiplash, because it was not all that long ago that that was the standard attack of the Right against the “postmodern” Left.
Because absurd opinion like "the earth goes round the sun" and "there's nothing wrong with being gay" were once "knowingly false and inflammatory" according to the overwhelming majority of people.
... therefore we need to keep protecting the speech of people who still believe the world is flat and that homosexuality is an affront to God just in case?
No, I'm sorry, that's an appeal to emotion disguised as rationality. We don't need to keep knowingly false, disproven and regressive ideas around any more than we need to keep arguing the merits of miasma theory, phrenology or the luminiferous aether. To say otherwise is to claim that truth cannot exist, merit cannot be measured and all ideas are equally valid... a premise already discredited by the value judgement made by your argument.