You are assuming that the net negative for society is never high enough to justify kicking liars and crazy people off your platform. That seems like a remarkable conclusion. Lets take for example Alex Jones spreading the lie that kids didn't die in school shootings and the people talking about their dead kids are making it up. Do you keep spreading it until a whack job kills somebody? Until some parent commits suicide?

What about health misinformation that if propagated will kill thousands? How many dead is enough to act?

What if false info about vaccines keeps enough from being vaccinated long enough for a new variant to emerge that infects the previously immune and the net effect is millions die?

I don't think you want to be elected Emperor over this at all its a shittier job than you imagine.