The January 6 attack of the U.S. Capitol was an insurrection, with plenty of violence and over 10 people convicted of seditious conspiracy. Trump continues to give aid and comfort to the violent J6 criminals. He failed to act on January 6th to stop the violence, and recently has called these convicted criminals "hostages".

I agree that the Supreme Court will find a way for Trump to avoid accountability. My guess is on first amendment grounds, over the meaning of "engage". Maybe with a pithy quote like "political speech is free speech and is never used to engage in insurrection".

The House of Representatives impeachment accused Trump of "incitement of insurrection".
“There’s no question — none — that President Trump is practically and morally responsible for provoking the events of the day. No question about it. The people who stormed this building believed they were acting on the wishes and instructions of their president,” McConnell said. “The leader of the free world cannot spend weeks thundering that shadowy forces are stealing our country and then feign surprise when people believe him and do reckless things...
“By the strict criminal standard, the president’s speech probably was not incitement. However — however — in the context of impeachment, the Senate might have decided this was acceptable shorthand for the reckless actions that preceded the riot,” McConnell said.”
c-span.org: Minority Leader McConnell Says President Trump "Practically and Morally Responsible" for January 6 Attack on Capitol | Video

Trump has been indicted for:
Conspiracy to defraud the U.S.
Conspiracy to obstruct an official proceeding
Obstruction of and attempt to obstruct an official proceeding
Conspiracy against rights