Companies don't want to be tied to hate speech or speech that causes people to riot. It may not seem fair, but companies are private and not a part of the government so there is no freedom of speech.
I feel sorry for radicalized Republicans. They can be reached. Banning, deplatforming and isolating is the opposite of what we should be doing. Big tech should be creating more platforms for them, and more outlets for expression and diversification, not less.