The problem interpreting the intent of that tweet is that Lucy Connolly herself admitted to authorities she was inciting violence so becomes hard to build a defence at that point. Incitement isn’t first amendment protected in the US either https://codes.findlaw.com/us/title-18-crimes-and-criminal-pr...
The major part of this case is that without a jury trial he'd probably have had zero chance of being cleared. Countless others were persuaded to plead guilty to avoid a long time in prison and then were given long sentences. h
he was strong enough not to give in.
You are right, freedom of expression in the US doesn't cover inciting violence, but it has an high bar, imminent lawless action:
