Perhaps it’s time to stop grouping the Constitution and online services. I don’t recall anywhere that mentions Twitter guaranteeing free speech.

If users (trolls) are uncomfortable with that, they can find another platform to abuse.

As you mentioned, Twitter really is at a tipping point. Perhaps it should become a paid service? Reading tweets is free. You want to send a tweet? Then you need a subscription.

People might argue that that will stymie growth from the casual, non-techie user. But if those same casual users aren’t really using the service anyway, it’s no loss.