The problem with the “something that damages the ability of society to make decisions” it’s with who establishes that and what’s the self correct mechanism those institutions that establishes that has.
You seem to imply that this is some metaphysical discussion on the nature of "truth" itself or who gets to be the arbiter of that - but I feel this is a dishonest digression here. Yes, truth can never be truly established - but both you and I know that Chamath's take on All-In for this particular claim was clearly false.
I agree with the poster you replied to. I guess you have a point in that there is no law that can tell Chamath to shut up and only open his mouth when he is talking about something with high confidence - but when you are speaking to a large audience on matters of economic policy with some implications as to what people believe then YES - you have a responsibility! The punishment to which breaking it should be (for people with a huge outreach like Chamath) being shamed online for it. People should learn the fact that Chamath is a man who chronically opines constantly about things he has no basis for having an opinion on. He is a chronic borderline liar.