Deplatforming/cancelling is person C _asking_ person A not to communicate with person B, under threat of person C no longer communicating with person A.
Your statement is not true.
https://en.wikipedia.org/wiki/Censorship
"Censorship is the suppression of speech, public communication, or other information, on the basis that such material is considered objectionable, harmful, sensitive, or "inconvenient." Censorship can be conducted by governments, private institutions, and other controlling bodies."
> controlling bodies
My point still holds. Asking a company to deplatform someone under threat of boycott is not censorship; because no individual user is in control of the platform.
Even your example of deplatforming is a very questionable practice, for instance it is often used by cults like Jehovah Witnesses to disallow followers talking with family members who leave the cult.
Cults and similar certainly do use their ability to sever association to control their membership, but making that step and severing those bonds frees those same members from the harm of the cult.
it's a big hard to grasp, but just because you are for something doesn't mean you can't be against an individual participating in the thing you're for doing bad stuff.
Being intolerant of the representative of somewhere between 20% and 40% of the country (accounting for turnout) is not a sustainable strategy. Ignoring even 10% of a country is a recipe for great pain.
That said, I'm still conflicted about this. I think it's possible to believe both that 1) there is a material threat of violence from continuing to give the president the equivalent of a giant megaphone, and 2) giving private corporations unilateral decisions-making power over who gets a platform is probably not in the long-term best interests of democracy.