There is nothing in the Constitution that says you aren’t allowed to challenge an election. There is a legal process to do so, which is what President Trump believed should be followed. But it wasn’t even attempted anyway.
There was no armed “insurrection”, only a protest against an obviously rigged election.
There was an armed insurrection. I watched it on TV, waiting for the National Guard to show up and shoot the people overrunning the Capitol and beating up the police in the building.