Nobody designates “white supremacy” or “fascism”, as Balz says, terrorist organizations. Because they’re philosophies, not organizations. The “Boogaloos” could be designated a terrorist organization.

Antifa is a set of principles (flawed, based on an erroneous view of history, and evil, in that it arbitrarily decides who the fascists are to beat down), so it’s not an organization that can be designated anything. Any specific group that claims to follow Antifa principles can be designated a terrorist group.

That designation has to be based on specific acts with evidence tying it to the group under suspicion. But sure, saying Antifa is a hateful philosophy that leads to violence, like white supremacy - that’s valid.