Popper was talking about tolerance in general. Tolerance of hateful actions, in general, is counter-productive. Tolerance of speech in particular is not, as speech alone does not and cannot "destroy free speech".

> Karl Popper was a well-regarded 20th century philosopher

I'm aware and don't see why an appeal to authority is necessary. Also OP didn't link Karl Popper. They linked a rando-streamer who's opinions on censorship probably have Popper rolling in his grave.

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Just for the sake of this thread here's Popper's conclusion from `The Open Society and Its Enemies: The Spell of Plato`:

> . . . In this formulation, I do not imply, for instance, that we should always suppress the utterance of intolerant philosophies; as long as we can counter them by rational argument and keep them in check by public opinion, suppression would certainly be most unwise. But we should claim the right to suppress them if necessary even by force; for it may easily turn out that they are not prepared to meet us on the level of rational argument, but begin by denouncing all argument . . .

This may seem like a logical conclusion, but it's based on a paradox and therefore inherently illogical. A paradox is usually useful for showing issues with a conclusion and not supporting one.

Consider who decides what is tolerant or not. Do the Karl Poppers (who was very opposed to totalitarism) decide? How about the linked youtuber, who blocks everyone with slightly opposing opinions? What if I consider the youtuber intolerant?

By not tolerating the intolerant, that person person should therefore not be tolerated. How could such a thing possibly be realized?

In similar fashion to the capacitor switch paradox, [1] it stems from an inaccurate model. Toleration is an abstract idea modeling a much more complex social trait. Abstraction models may make reasoning as humans easier but we should always be careful when applying them.

[1]: http://www.users.on.net/~ithilien/tam/electronics/CapacitorP...