True Left

"1. If I take the person's soap box away, have I curtailed their speech? No, I have not. The person can still say whatever they wish and to whomever will listen.
2. If I take the person's megaphone away, have I curtailed their speech? No, I have not. The person can still say whatever they wish and to whomever will listen.
3. If I take the person's crowd away (cancel culture), have I banned their speech? No, I have not. The person can still say whatever they wish, it's just that no one is listening anymore."

This formulation is confusing. Whose property is the soapbox/megaphone? In the case of social media platforms, it belongs to the business which lends it out, hence they can stop lending it to whomever they want whenever they want. But your wording above makes it sound like the speaker owns the soapbox/megaphone.

I understand Cancel Culture to mean taking away the soapbox/megaphone (owned by the business). I'm not sure what you mean by taking away the crowd separate from taking away the soapbox/megaphone. How? By kidnapping them? This just adds more confusion.

"4. If I hold the person down and staple their lip's shut, have I banned their speech? No, I have only limited it. If the person still has both hands they can write, type, and perform sign language."

This is also a confusing example.

"5. If I throw a person in prison for something they said and banned them from speaking or writing to anyone, have I banned their speech? Yes!
6. If I kill someone for something they said, have I banned their speech? Yes, I have!"

There is a difference between imprisoning or executing them in the middle of their speech so as to prevent them from finishing their speech, and imprisoning/executing them after they have finished their speech as consequences for its content. The former was despised in the ancient world, as it suggests fear of what might be said. The latter is part of statism in the ancient world. The monarch has a duty to hear anyone who wishes to speak; the speaker has a duty to show willingness to die for their cause. In some cases, even when the monarch does not request death but merely is unpersuaded by the speech, the speaker would commit suicide anyway in order to show conviction to their issue they just spoke about. This system thus automatically filters out trolls and other non-serious speakers, a feature that is utterly lacking today, hence leading to: