If you cared about "cancel culture" and platforms having too much leverage, you'd be a lot more concerned about this duopoly than whether Twitter lets Nazis speak.
They're not the government. They've no obligation to platform anyone at all, whatever sort of extremist they are. Get used to it, examine why the world will be a better place, move on.
That's just objectively false we have a long history of forcing companies to take customers from Utilities, Americans with Disabilities Act, anti trust laws, forcing companies to license technology, and a whole bunch of other ones when needed; This is no different.
We are talking about it because we find the current state with Visa and MasterCard as unacceptable.
I don't think that the town squares and forums of the internet should be controlled and paid for by advertising companies. Nazis are not banned on any moral or political basis: It's purely a buisness decision. It sounds fine but when you begin spouting some unprofitable ideas they're not going to hesitate to ban you too.