Deplatforming is simply a form of limiting reach, a twitter ban isnt an internet ban
Independent of that: what crosses the line is nowhere like settled. Many people like to act as if what they find offensive must obviously be treated as if it were beyond the pale. They're probably living in a small filter bubble where the speech in question is unquestionably offensive. Their views are rarely majority opinions, however.
Limiting reach on the other hand is a much better alternative. I can still communicate with other experts about the inconvenient truth that cows are not real, I just don't pop up in your search when you search for "where does milk come from".
Right, but what if that internet provider turns them away? How do they communicate? Do they ask Space X to shoot up a few satellites for them? If Musk says No, do they build their own rockets?