If they really do storm the White House, the media can't ignore that and the Secret Service will open fire on them...and then that will be the terrorist act that gives Trump and Barr the blank check they need to drop the hammer on Antifa and BLM full force.
As of Sunday, the DOJ already considers Antifa to be an international terrorist movement that can be subject to the penalties of things like the Patriot Act and they can more or less financially shutdown and charge anyone who throws their lot in with Antifa.
The problem is that Antifa isn't a foreign actor, its an insurgency that has governors, doctors, teachers, police, soldiers, nurses, celebrities and their children as sympathizers if not outright members. If Trump comes down on Antifa hard, that might give some of those insurgents the push they need to declare an actual insurrection and a proper civil war starts.