Hmm ok, but it still sounds kind of sus. One of the insights of the Mixmaster era is that what really matters is the amount of message reordering you can do, and that's why remailers typically had 24 hours or more of latency. So I've never believed in Tor (near real time). Even with a text chat network, more than a few seconds of latency will have a significant usability hit. And also, as mentioned, using the service at all probably makes you into one of the usual suspects.

The Guardian (newspaper) handles this in an interesting way, for 1-way communication from users to the Guardian itself. They have a news reader app used by millions of subscribers to access news articles and stuff. And if you want to send them a confidential news tip, the app has a feature where you can enter a text message for their editors. The news reading protocol includes some space for this type of message in every transaction, under a layer of encryption so that an eavesdropper can't see if a message is present. Allowing user to user communication through such a scheme could easily lead to mayhem, but for sending stuff to an identified recipient (the Guardian) that has some establishment cred, it's clever.