The mob was told by Trump that they were going to the capitol to undo the will of the voters and take power. They went, got inside and threatened legislators. They disrupted the certification. Trump, the coward, did not go with them.
I’m not sure why you are so worried about this being called a coup. Your argument reminds me of those who think imprisoning immigrants, snatching their children and forcibly sterilizing women doesn’t constitute concentration camps.