The only justification, imo, for extrajudicial vigilante violence (i.e. not self-defense) is if the state has collapsed and has failed in its duty to protect its citizens (i.e. POC, LGBTQ, etc.). Now, I think you can make a credible argument that the police forces in many jurisdictions are inequitable enough to make that violence morally justified.
The question that I have that antifa has wholly failed to answer is: what next?
Either you choose to reform the state to protect those that are not protected, or you destroy the state itself.
I just don't understand 1. what Antifa's goals are (it seems like there are two wildly divergent camps within antifa: the far-left and the anarchists) and 2. how they can ever hope to accomplish them. Otherwise, they are just a group without an ideology that inflicts wanton extrajudicial violence? Very 'Anonymous' to me.