Trump's speech is probably defensible in every court — except, perhaps, the Senate

 https://www.nbcnews.com/politics/donald-trump/trump-s-speech-probably-defensible-every-court-except-perhaps-senate-n1254258

Even if there is proof that Trump "intended" to cause violence with his speech, and even if there is proof that the violence he intended to cause was the storming of the Capitol, there could be an issue of whether the violence was "imminent" enough to be criminal.

Some will conclude that words like "fight" and "strength" gave the crowd the detailed instructions to violently enter the Capitol. The Senate can still convict even if reasonable minds can differ over those factual conclusions. A criminal jury must be unanimous.

A criminal jury is bound by the reasonable doubt standard. The Senate is not. It is bound by the two-thirds supermajority vote standard — and not much else.