There's not multiple Antifa's, there's one, which is Antifa, if people don't agree with it then they don't support it, so the ones that do support it do incite violence and the harming of others, for example look at that European reporter who tried to do a news piece in front of one of their hangouts, they were chased out all the way to their car blocks away while having bottles thrown at them, and then look at the $100,000 in damages in Berkeley.
Also calling something a movement does not remove it's negative connotation.
I already said that it's a negative connotation. Just because something is a negative connotation doesn't mean you have the power to completely change the united states' legal system to declare an ideology as terrorism.
either way, the only 'antifa' entity i've ever seen is the anti fascist network, which already on its own website states that the grassroots groups are working independently to stop fascism, not as a collective. There are antifa groups across the world, all over europe and in the united states. unlike a real legal terrorist group, its just a bunch of independently acting groups that are protesting in both nonviolent and violent forms. The nonviolent ones are clearly organized, while the violent ones are random people who break into a mob or show up separate from the others and cause violence.
the attack at the milo thing and that stinkbomb incident are probably domestic terrorism under our legal system, but there's no connection between the two besides the fact that they were committed by people who fly the same flag.