Honestly I'm mostly just venting, others already replied, and then we got the inevitable "well okay if it's that big of a deal you don't need to tiptoe around it" post in response, but does anyone else have a playbook for dealing with this tactfully but directly?
These are people who are not wreckers, just sort of naive, as far as I can tell, but of course you can't know for sure. They've said shit like "well then where am I supposed to I'm a revolutionary, I'm not afraid of anything" (phrased a tiny bit nicer) in response to being told "hey keep in mind these chats are almost certainly monitored"
its like, hey, obviously people are being cagey because they don't want to denounce direct action, but also don't want you to blow up the aboveground org by being needlessly purposefully reckless in communicating about your planned heavily implied crimes. But I don't even want to explain that head-on because in that response I'd also be endorsing direct action in a semi-public forum, or tiptoeing around it the same way the other responders did. Like I want to say, and would say if we were in person, that this is an aboveground org and that you can probably use this as a network to find likeminded individuals but you're going to have to build out a little bit of trust by talking to them in DMs or in person and put together a smaller group that's not directly attached to the org, because we can't have your grudge blowing up the whole thing.
How hard is it to chat one-on-one and form a smaller more trusted group? Just because you don't fear repression doesn't mean you shouldn't take any precautions jfc
people are way too fucking open about their feelings and internet-brained, feeling like "well if I can't fedpost in this specific groupchat then where am I supposed to do it???"
I mean fuck maybe they are wreckers. But I feel like its usually marginalized people who are most like this, maybe because of feeling like they have nothing to lose, so I don't feel like we should just push them away either
I could message them privately but ultimately then 1) I've got a target on my back if they are wreckers and 2) I feel like I'm basically whitesplaining to them
I'd gently but firmly state that discussion of crimes should be kept offline and out official meetings. I'd make this statement "to the room" as it were.
OpSec is important even for perfectly legal antifascist organizing. Feds are not the only infiltrators to be cautious of. There's no way your org is mature enough to be operate as a recognizedly criminal organization. At this stage, to remain operating openly and legally, members who wish to engage in illegal acts must do secretly so as to not implicate the broader org & its membership.
This is partly why I like Matrix. a self-hosted (by the org), unfederated server provides an official private means of communication for the organization, but messages are only visible to the participants of the conversations, and the metadata of who's talking to who never leaves the server. It would be totally normal for members to have private conversations, why would we assume they're discussing crimes???
This org does not condone illegal activity! 
yeah this is probably the approach I should have taken. And same, if we get organized enough to merit a matrix server I do have the skills to run it, though I'm sure many would balk