Those articles are using the word 'antifa' as a slur, not as an organization.

It is like saying "the woke mob silenced a speaker", it doesn't mean anything. There isn't a 'woke organization' that is planning anything

A movement is better terminology than an organization, fair.

But okay - I'm confused what sources you would accept? There are "Antifa" groups on social media that literally advocate for doing this, I've seen it first-hand.