I realize this is an old post but this is a dangerous message.
"We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant."
Who are the "We" in this statement? and who are the "intolerant"?
Since this was presumably written by a member of the "open society" it would appear to imply that the "we" are the ironically named "Social justice warriors" who do not support Social justice and claim that White Nationalists are intolerant and are responsible for violent protests.
This is a bare faced lie, and White Nationalists can equally claim that it is the "Social justice warriors" who are the ones who are intolerant and responsible for the violence that occurs at protests.
All you have to do is to watch the footage of any of the White Nationalists protests to see who the ones who initiate the violence are, and it's not the White Nationalists.
I fact in virtually every case it's the ironically named "Antifa" who cover their faces and come armed with everything from baseball bats to bottles or bags of urine to pepper spray and home made flame throwers. While the White Nationalists only bring helmets and shields to protect themselves.
Don't just take my word for it. Watch the videos and you'll see exactly what I'm saying.
The truth of the matter is that the Socialist/Communists can't make any reasonable argument for their position since their position is not reasonable, so instead they come out in force to violently prevent the Nationalists from being able to make any reasonable arguments for their own position, and then blame the violence (which they themselves have initiated)on the Nationalists.
The leftist controlled media then reports that the White Nationalists held a violent demonstration but conveniently omit to mention the fact that the leftists were the ones who caused the violence.
Then we have people like ― Karl R. Popper encouraging people who believe in tolerance to be intolerant of White Nationalists protests/rallies. In other words he is saying they should be prevented from holding protests or rallies. This would violate the Constitution so it can't be done lawfully. The only way it can be done is by violence,
So he is effectively condoning and inciting violence, which is a crime.