Twitter, same as every other corporate entity, benefited from Trump's tax cuts. They went years without silencing him, despite cries that his posts were dangerous. They -wanted- to keep him on their platform; he kept millions engaged with it. They even created 'world leader' exceptions -just so they wouldn't have to apply their own terms of service against him-.
It is disgusting how people act like this is bias against Trump/the GOP, when it's so obvious that the bias flows the other way, and it took an actual armed invasion of the US Capitol for these companies to finally step up and do something.