The version I heard was a bit different - I have no sauce but the poster in question (another forum) is usually very good with analyses.

Story goes a homeowner came down to tell them to piss off, and got attacked.

Not smart. He’s in the local Gypsy Jokers biker gang. So defended himself. His biker friends aren’t happy with Antifa now. Probably never were in fairness, but if this is true they are really pissed.