Your definitions of unacceptable speech & legitimate threat are unclear, and people nowadays make claims loosely. If it means demonstrable harm, then they’re fine & I apologize for the excessive caution.

From context

Rawls emphasizes that the liberties of the intolerant should be constrained only insofar as they demonstrably affect the liberties

and key words

only when the tolerant sincerely and with reason believe

and my direct statement

speaking one’s mind is not an act that directly & demonstrably harms/threatens security or liberty

I’m stating reasons of demonstrable harm are largely absent in speech. Speaking one’s mind doesn’t cause harm. Harm requires an act.

Tolerance is the allowance of objectionable (expression of) ideas & acts. That objectionable acts directly & demonstrably harm/threaten security or liberty is an easier claim that fits Rawl’s conclusion consistently. That speech alone can do so is a more difficult claim: maybe only false warnings or malicious instructions that lead to injuries or loss of rights, coercive threats, or defamation.

The paradox of tolerance is a concept, not a unique conclusion. Philosophers drew all kinds of conclusions. I favor John Rawls’:

Either way, philosopher John Rawls concludes differently in his 1971 A Theory of Justice, stating that a just society must tolerate the intolerant, for otherwise, the society would then itself be intolerant, and thus unjust. However, Rawls qualifies this assertion, conceding that under extraordinary circumstances, if constitutional safeguards do not suffice to ensure the security of the tolerant and the institutions of liberty, a tolerant society has a reasonable right to self-preservation to act against intolerance if it would limit the liberty of others under a just constitution. Rawls emphasizes that the liberties of the intolerant should be constrained only insofar as they demonstrably affect the liberties of others: “While an intolerant sect does not itself have title to complain of intolerance, its freedom should be restricted only when the tolerant sincerely and with reason believe that their own security and that of the institutions of liberty are in danger.”

Sacrificing freedom of speech is unnecessary for self-preservation in extraordinary circumstances as speaking one’s mind is not an act that directly & demonstrably harms/threatens security or liberty.

Where’s the part where they act on these detestable ideas & we’re powerless to stop these acts & hold people accountable for their actions? Behaviors are acts (distinct from speech) and I see only claims to defend speech.

Unless you exterminate everyone you disagree with, people with ideas you disapprove of will always exist. Better to know who they are by letting them tell us. Civil liberties & a right to exist apply as much to them as to you.

As you wrote, people are malleable. They don’t need the input of others to develop incorrect ideas & common biases on their own especially from an early age. As that article on early childhood development of racial prejudices points out, avoiding talking about discriminatory biases or delaying the topic is not the answer. Early intervention with active, explicit conversation is important to correct biases & misconceptions acquired from implicit social factors, which suppression of speech will not prevent. With appropriate work, people can & often need to be corrected.

Agreement through suppressing opposing ideas is unreliable & inadequate. It doesn’t correct self-learned biases. It assumes people will only hold unopposed ideas, which indicates they never reliably held them. If an idea has any merit, people should hold them despite flawed challenges, because we did the work of educating them properly & they know better. Choosing to compromise freedoms instead is flat out lazy & an insult to everyone’s dignity.

Finally, it’s pretty asinine to assume we need to sacrifice civil liberties to gain civil liberties. In the United States, the free speech & civil liberties movements gained together. That happened despite worse racism then with Jim Crow laws & white supremacists speaking freely. If we were able to gain civil liberties then under harsher conditions, then we shouldn’t have to sacrifice them now.

Insistence on classic freedom of speech doesn’t mean centrist, moderate, or apolitical. It means supporting civil liberties without being an ignorant hypocrite that takes those hard-fought liberties for granted. There was a whole movement that was pivotal to the civil liberties movement.

But promoting ideas of racial supremacy directly encroaches on others’ basic freedoms and safety.

Does it? I’ve never seen that proven convincingly. It goes against my experience lived embracing the tired old saying sticks & stones may break my bones, but words will never hurt me around detestable assholes spouting particularly offensive ideas at me. Realizing that expression gave me power: their words matter not a damn to me as long as they don’t turn into action. Once they turn into action, however, a warning to call the authorities usually settles the matter uneventfully.

Words are bullshit. Anyone can put words together: they’re just noise. People can spout nonsense forever & form their nonsense echo chambers as long as nothing comes of it. Their words are not the problem, they’re an indication. Actions are the real problem.

If you don’t want people putting their offensive ideas into action, then stop them, not their words. Block that legislation from getting through. Argue their ideas are garbage. Change the minds of those in power. Educate more people to your side.

I’m disappointed so many people detract a key civil liberty so easily & need the obvious explained.