Well you told me my initial interpretation of what you said was wrong, so I tried to find an alternative meaning behind what you were saying. But now I see my initial interpretation was accurate. You are indeed saying that, if Twitter isn't omniscient, then it won't be able to avoid being used to oppress and propagandize because it's not possible moderate perfectly. This is the just the perfect solution fallacy.

  "free marketplace of ideas"

This is a culture war talking point that is ignorant of the reality of social psychology and the social contagion of bad memes. Suicide contagion, stochastic terrorism from ISIS supporters in Europe and white nationalists in the US who were mostly radicalized online, the rise of populism in the US since 2015, wokeness ideology spreading to all institutions in a few years. You think you can just shine a light on bad ideas and they'll go away, but the exact opposite is true if they play to people's tribal instincts and resentments. Heck the rise of fascism last century was partly memetic propagation due to the mass production of culture. If you want to form a worldview based on social psychology, then it should actually be based on social psychology.