Trump's victory was not the last gasp of laissez-faire moderation by the big companies. As you've noted, they allowed people to use their service for what people wanted after that day.
The end of his Presidency, though, is a different story.
Indeed, Twitter, upon being forced to decide whether their laxly-enforced TOS meant they'd have to kick a sitting President off their service or whether they would find a way to avoid that scenario, modified their TOS to allow him and his ilk to stay.
... and the consequences of that decision were that their CEO, four years later, got hauled in front of Congress to talk about what their communications service facilitated on January 6, 2021, and whether they should have done anything differently.
They tried their damnedest, they really did. They don't actually want to be some kind of benevolent dictators over what people see and hear; it's not the job they set out to have. But they've seen what happens now if they don't assume the responsibility their size has thrust upon them.
We're now at the beginnings of the experiment where they assume the role of benevolent dictators, and the results remain to be seen.