[smaudet]

Safe encrypted group chat with stangers is an oxymoron.

Locking down a platform is not an acceptable solution to the above conundrum - it doesn't matter if the user is using an official device/app whatever if they are untrusted. They can always turn around and leak everything you say without any technical measures.

Should we have no security? No, if you want to color messages differently based on perceived platform, fine. This is just an illustration that no technical measures can replace the fundamental trust necessary in these types of situations.