Your number two is just flat wrong. The best opinions don't naturally rise to the top in all situations. Mainly because the interpretation of the best opinion is subjective. That's why apartheids happen, because sometimes in the larger region the interpretation of the best idea is abhorrently terrible.
It's entirely fine for a private place (which this forum technically is) to curtail what people are saying in it. Yeah people are allowed to have terrible opinions. In no way is someone obligated to let those people use their private space as a soap box and amplifier for things they don't want amplified.
Those terrible people can go make their own terrible spaces to say terrible things, and I'm going to read it, and then I'm going to take it back to my space pick it apart and defame the terrible things they are saying and explain why it is terrible to whoever will listen. Hopefully I can dissuade at least the people that listen to me.
You're certainly not obligated to do anything. But what you're describing here is a great way to insulate yourself from other ideas, and exist in a perpetual echo chamber.
It's a rejection of the underlying principles of free speech.