> ISIS sympathizers, Nazis, Stalinists, or pedophiles do not have a right to be protected

> If a minority calls for violence, [or ...], then the general duty to protect minorities need no longer apply to this minority.

That's quite different. You should have just said that in the first place. Banning people for calling for violence/etc is completely different from banning them for their beliefs or sexuality which is what your first statement said. I still don't agree with it though.

> No, it's one meaning and there is no contradiction. The phrase was coined by Sir Karl Popper.

I'm sure you know my confusion, but I'll say it more clearly. If you're intolerant of the intolerant, then you are intolerant yourself, so according to the rule, nobody else needs to be tolerant to you. From your examples, it looks like you do have two meanings of the word "intolerant", contrary to your claim. There's intolerance of tolerant people and there's intolerance of intolerant people. The first is not allowed and the second is. So perhaps you should have said "There is no need to be tolerant towards the intolerant of the tolerant.".

> Posters should be banned if they violate the basic laws of civil discourse (be kind, don't troll, don't be a racist, don't call for violence, etc.) or intentionally instigate violence or promote crimes.

This is OK for a rule to maintain a stable society, but it's a society which can't change if it's applied everywhere. For example, if the society didn't already have gay rights then it wouldn't gain them because nobody would be able to talk positively about it. That would be promoting crimes. That's how it is in Saudi Arabia - you're not allowed to promote homosexuality and your rule would entrench that cultural norm. Another problem is the definitions of racism, trolling and kindness are subjective so they would end up simply being whatever arbitrary cultural norms the society already had. Your idea seems to be simply "if it's my forum, I can do what I want", but that misses my entire point about the scale of the influence that Facebook/Twitter/etc have on the world. I don't think Mark Zuckerburg should just be allowed to delete all criticism of the Republican party from Facebook, for instance. You think he should because his forum, his rules.

> If someone calls for the destruction of your society

That's incredibly subjective. I don't know what example you're thinking of with Steve Bannon, but where do all these examples fit? It sounds like you want to ban calls for all of them!
"Build a motorway through that suburb"
"Texas should succeed from the US"
"Alcohol should be allowed" (would destroy an alcohol free devout Islamic society)
"Open borders" (would destroy a society by reducing the shared cultural values)
"No immigrants" (would destroy society adapted to ongoing immigration)
"Invade Iraq and remove the government" (destroyed a society)
"Wipe out ISIS" (destroyed the society of ISIS)
"Imprison people for possessing cannabis" (destroyed black society in America)
"Ban people who call for destruction of your society" (would destroy their online society)
Nearly any grand social change would destroy a society in some way. How do you judge what's allowed and what's not? That's too big a question to just make a blanket global rule for on all the big social media sites.

I think there's important value in public, anonymous, social-norm breaking discussion. It allows the status quo to be challenged without the person being subject to personal real world retaliation. Trolls of the type that say knowingly false things to anger people and then laugh at them have value because knowledge of their existence helps people to stay reasonable and not succumb to expressing blind anger at opinions they don't like. Instead, you're encouraged to respond intelligently and honestly knowing that at any point the troll might say "Haha, just kidding, I don't really believe that but now you've shown that you can't defend your belief and are irrational yourself!" I've learnt quite a lot of things by arguing intelligently with trolls. Not things they told me, but things I researched myself in an attempt to convince them. A clear example of this type of troll is a flat Earther. Do you intolerantly dismiss him as a troll or improve yourself by convincing yourself the Earth isn't flat by some means other than appeal to authority or popularity? I think those are the reasons most people believe the Earth isn't flat and are the same reasons most people used to believe God created the Earth. So they're not very good justifications for a belief.

> If I have a forum and don't want Nazis to use it as a platform, I have the right to ban them, just as I have a right to ban motorcycle enthusiasts from my rose gardening forum. Users of private forums aren't entitled to anything.

I agree but I've already explained that "I think big social media companies have so much power over so many people that they should be required to give greater freedoms to their users than small forums are."

Your rose gardening forum is a "small forum".