From my experience so far in my pre-branch, we have been much better at maintaining our signal chats, restricting old users from the chats and not retaining old messages in previous temporary chats. I believe this is more of an issue with this local chapter, and I am glad that at least this wasn't a dangerous person as you suggested burning the chapter. I can see your viewpoint, but I think the first thing to be done is to privately message the party so that we can internally discuss this and resolve the matter through democratic centralist means. That's appropriate for any situation generally, and perhaps if this escalated and the party made poor decisions after this, then bring this to the attention of the national party, and then maybe mention it publically without exposing sensitive information (and censor a little better when showing screenshots).

I hope I am not saying too much, but I am also working on alternatives for google products within my pre-branch, and other members were going to mention their concerns about the security of using big tech tools before I suggested to help. I'm just one IT person, and I am already contributing a major difference as this pre-branch grows.