The answer to this question is obvious - it's an exercise of pure power. Any time you hear anything about "misinformation" the real thing they are talking is power. Whoever has the power can censor those that do not have it and deny them chance to express their views. The guise under which it is done is immaterial - today it's health, tomorrow it's climate change, next day it's electoral politics or terrorism or vegetarianism or gender issues or bee colony collapse. Anything can be used as a basis for censorship, once you have the power and the will to censor. And the power to define what "misinformation" is and the power to censor is one and the same. It's not about seeking the truth, it's about seeking control and domination.
Once, in America, it was universally acceptable that censoring speech is not the power somebody should get. Neither the government, nor anybody else. Of course, as with every ideal, the reality sometimes came short of it - there are many infamous examples of censorship, both governmental and otherwise, that happened in America. But those ultimately were realized as conflicting with the ideal - and ultimately, the ideal won and they have lost.
Today, this ideal is increasingly being abandoned - for the large parts of the Left, have already completely been abandoned - for the ideas of "safety" and narrow partisan political considerations. The nation - and the whole culture we call "Western culture" - will suffer a lot and regret a lot if we don't find a way to stop it.