Well done, sir. This is why nobody takes libertarians serious.

In the end it doesn't matter if it is a leftist or a rightist organization that calls for murder or other criminal or sedituous behaviour: if we can be sure that you use your means of communication to murder people and destroy society, then this has consequences. In Germany I know as well of leftist as rightist groups/activists who were prosecuted on these grounds, so this is by no means something that is just used against nazis.

However: almost all nazi-groups are concerned by this, as violence and hate are constitutive for their movement, while almost all of the leftist groups go uninvolved, since their fundamental interests are compatible with our basic humanitarian values etc.

So, to all you libertarian-nerds: stop whining (and seeming stupid thereby) that it would be sooooo hard to detect speech that is used to murder people, poison the civil society and destroy the democratic form of government. There is nothing valuable about hateful agitation, we can do fine without it. And please stop acting as if it didn't matter: the whole point of the Charlottesville-demonstration was to show that people can be motivated by hateful agitation and propaganda on the internet to go out and intimidate the rest of the world. That people can be motivated to let go of all inhibitions if they see day after day that it is okay to talk about killing jews, homosexuals and afroamericans, that other people kudo them when they deride minorities themselves.

Oh and by the way: go and check your priviledges. It is easy to act as if hateful speech wouldn't matter if you aren't affected by it (or are intelligent and eloquent enough to turn the tables). But: hateful speech harms the people that are affected by it and can make life a living hell for them. I mean: it is obviously the aim of it, isn't it? I deride and intimidate minorities, so that ... they feel derided and intimidated. It's just that simple.

Fun fact: "Slippery slope" is the term used to describe the fallacy of logic in your sentences. The slippery slope fallacy lies in you rejecting the -- admittetly vague -- claim "Vulnerable people must be proactively protected." just because you can imagine that bad things might happen if this mind-set was applied excessively.

This is a fallacy of logic, since it leads you to reject a claim just because it is not as precise as you'd like it to be. However, a claim isn't invalid per se just because it is vague.