alt Hacker NewsWhy do you think these volunteers supported the attack? I don't think there's a published statement to the effect. Even the U.S. government does not claim that (at least not in its written communication).
The perpetrators very likely used Apple and Google services, too, and no one views that as some sort of endorsement by the companies.
By stating "Antifascism and anticapitalism are not terrorism" you create a hard statement: Anything labeled as anti-capitalism is not terrorism.
And far too often people downplay their violence and ruthlessness by using those labels as an excuse.