There was no call for lawless action by Trump. Instead, there was a call for a protest at the Capitol. Moreover, violence was not imminent, as the vast majority of the tens of thousands of protesters were not violent before the march, and most did not riot inside the Capitol. Like many violent protests in the last four years, criminal conduct was carried out by a smaller group of instigators. Capitol Police knew of the march but declined an offer from the National Guard since they did not view violence as likely.
So Congress is now seeking an impeachment for remarks covered by the First Amendment. It would create precedent for the impeachment of any president blamed for violent acts of others after using reckless language. What is worse are those few cases that would support this type of action. The most obvious is the 1918 prosecution of socialist Eugene Debs, who spoke against the draft in World War One and led figures like Woodrow Wilson to declare him a “traitor to his country.” Debs was arrested and charged with sedition, a new favorite term for Democrats to denounce Trump and Republicans who doubted the victory of Joe Biden.