Remember this guy?
https://boards.straightdope.com/sdmb/showthread.php?t=833962
He’s now claiming to be an FBI informant against Antifa.
This is confusing. Wouldn’t he have to be a member of Antifa to be an informant against them, and why does the far right consider this to be scumbag behavior?
He could have just been talking straight out of his ass. He could also have seen things that are illegal without being in the group. He’s not that reliable of a “bystander” witness but that doesn’t absolutely mean he wouldn’t have been interviewed by police. Giving a single statement with an elevated sense of self-importance could lead to his claims.
He might have previously infiltrated them and actually have something from that time. It would be much harder after he got internet famous but never underestimate people’s ability to be stupid, ignorant, or both.
He might have even been involved in groups that shared membership with anti-fascist organizations. There’s some spillover between the extremist groups along with individual movement among people that are just testing things out until they find the right fit as they radicalize. One of the possibilities is he started out with, or was exposed early to, “greenwashed nativism.” That’s a movement to spin nativist themes in terms of environmental concerns. I’ve even seen reports of small nativist, green-focused, anarchist groups. (Talk about a fringe of the fringe. 
) It’s entirely possible he started his journey of extremism among the left’s extremists before ending up with the right’s. He might have some real, although older, information from that time.
I’d still lean towards this whole conversation being pulled out of someplace uncomfortable. I don’t mean the back of a Volkswagen.