And that's the problem.
This story is natural clickbait because you have literal fascists claiming to be anti-fascist, which is an obvious contradiction.
But if Antifa is just anybody who is against fascism then violent anti-fascists are Antifa. You can't say they're not when they actually are against fascism. And without any official leadership to disavow the advocation of violence, now your label is tainted by violent evildoers and you get to enter the grab-bag of boogymen for whenever somebody needs one.