If you read the essay carefully, you'd understand that in every era "right thinking people" are sure that the things they want to ban are bad. In 1700 after explaining how broad-minded you were you'd be saying "Nevertheless, I'm sure it isn't a mistake to consider atheistic propaganda to be harmful to society." And you'd be wrong.

The whole point of the essay is that you have to step out of yourself to have any hope of seeing beyond the prejudices of your time, and that this is extremely hard. Your casual use of blanket labels for forbidden ideas is a sign you don't appreciate the difficulty of the problem here.

You'll notice I have never said what kinds of speech I think should be banned. That's because I've seen enough to know that that that second clause following "I'm pretty open-minded, but..." is very likely to be mistaken. Like someone saying that some open mathematical problem will never be solved, you're setting yourself up to look like a fool to future generations.

So your use of "sure" to me is very convincing evidence that your filters will generate a lot of false positives. I spent a whole month thinking about this problem. WYCS took the longest of any essay I've written. And I would be very reluctant to use that word "sure" in this kind of situation. So either you understand this stuff so much better than me that you've passed through uncertainty and back into certainty, or you simply have the confidence in your opinions that everyone is born with.