If this was the totality of the tweets: https://www.northamptonchron.co.uk/news/crime/northampton-ma... then I think that would be protected speech in the US. There is no specific incitement or threat. In fact the first tweet seems to be along the line of: "if you did criminal act X then I would not care". There is also a reference to another tweet where it is claimed he says it was 100% the plan. Maybe this along with the original tweet would be a problem but its very difficult to make a judgement without seeing all the tweets. But there is a reason why the US has a very high hurdle for incitement because a lot of political speech which should not be considered incitement could be by a bad faith interpreter. For example people were making tweets saying 'Biden should order Seal team 6 to kill Trump'. If you applied your same logic purely on incitement grounds then surely these people should be criminally convicted as well. However, in this particular UK case the conviction doesn't seem to be based on incitement to a crime but rather inciting racial hatred was a component. I think in US law you might get tougher penalties for inciting criminal actions that involve racial hatred but it's not a crime in itself. The CPS seem to be claiming he was found guilty of "publishing material intending to stir up racial hatred".
> people were making tweets saying 'Biden should order Seal team 6 to kill Trump'
Such tweets were not "likely" to produce imminent lawless action, or even plausibly intended to do so. That's ultimately why they're regarded as protected speech. The case of someone inciting people to set hotels on fire in an ongoing riot is going to be quite different.
