Pollux JRay The
is_private column has already been added in
flarum/core, and is ready for the next release.
Later, what may happen when you update is that the PMs created before the update may not have
is_private set to true and may become public when the extension is disabled. Don't quote me on that, though.
If you want to talk about how it's not ready for general use, then keep in mind this is beta software, with beta extensions. Nothing is technically ready for general use here, yet here we are. ❤
Also, this discussion should be continued somewhere else.