This is where the propaganda surrounding American-style free speech clashes with reality. Many people assume it protects all speech unless it's incitement to imminent lawless action, "fighting words", etc. But that is simply not the case. This is in large part due to how American law doesn't do what it says. Read their First Amendment, actually read it: it's a limitation on Congress. It's become much, much more than that because their Supreme Court is a de facto legislative body.

This is how you get the Red Scare; that money is speech (Buckley v. Valeo); that legal entities are people with free speech and thus campaign donations cannot be restricted (Citizens United v. FEC); that retaliatory arrests for speech are fine so long as there's probable cause for something else (Nieves v. Bartlett); that therapists have a right to convert their underage gay clients (Chiles v. Salazar); etc. Did you not hear about Mahmoud Khalil? Or Alex Pretti? Ect?

The whole "objectionable tweets" thing is so overplayed too. British pundits like to wax poetic about the apparent persecution of people for political speech, and the "political speech" is, for example, Lucy Connolly calling for the burning down of a hotel building housing asylum seekers.

The biggest sufferers under UK speech restrictions are not tweeters, it's protesters, and yet the examples are always tweeters. Isn't that interesting?