Private chat rooms are solely used for moderation purposes, this is a hard rule by Stack Exchange. In most cases the information in such private rooms should not be made public, they often contain private information about users which moderators are forbidden to reveal by the moderator agreement. Apart from PII, there are often discussions about suspensions or user misbehaviour which should not be discussed in public.
There are several ways that private chat messages could be exposed:
- a moderator changes the room access to public
- a moderator moves messages to a public chat room
- a non-moderator is granted access to a private room
- a link to a message from a private room is posted in another public room and one-boxed
What I propose is to prevent a room that was private from being made public and to disable the ability to move messages from private rooms, or restrict it so that it is only possible to other private rooms. The ability to request access to private rooms should be removed entirely, and messages from private rooms should not be one-boxed in public rooms.
The first two cases are actions that simply shouldn't happen. If a room doesn't contain any sensitive information, it probably shouldn't have been private in the first place. And moving chat messages out of the moderator-only room is strictly forbidden anyway.
The third case has certain uses, so this should still be possible. But I'd remove the ability to request access to private rooms. There is no real reason to do this, anyone that has a reason to be in a private room should be explicitly invited by a moderator or SE employee.
The migration of chat messages out of a private room has happened in the past. I'm not aware of any case where a private room was made public accidentally, so this might be a theoretical concern and not much of an issue in practice. Still, I feel a bit uneasy that there are only two clicks that separate a large amount of private information from being made public.