I think misinformation is not really that problematic as the truth is valuable to most people and we seek it out all on our own. Its self correcting in an open society.
Note that he specifically says in that passage that he’s not advocating the suppression of all intolerant speech. Thus even if some speech were intolerant, that by itself would be insufficient for suppression.
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Misinformation is problematic to the extent that it endangers the open society’s very existence, and with it its ability to self-correct.
Many leftist would meet this criteria just as strongly ala "My <x> is not up for debate." or other statements conflating ones existence with ones identity with the same result: No discussion (outside a select, tautological group of gatekeepers) allowed.