I think @michelf has the key response to this feeling of exclusion, which I suspect is likely a motivating factor in a lot of the discomfort expressed in this thread:
Spaces like this are going to exist, whether in private message threads, off-forum communities, in-person conversations, or some other medium. This initiative provides a home for these spaces that is officially endorsed by the Swift project. If anything, this initiative will make things less secret: the reason we're aware of these community groups at all is because of a public blog post on Swift.org, after all.
IMO, it's far better to have these community groups as first-class members of the Swift community at large than to relegate them to loose, informal collections of marginalized Swift developers who must self-organize to find one another. The visibility afforded to an official community group will enable the inclusion of as many participants as possible, and leadership involvement/endorsement gives the work group a much more viable path to action on any issues, ideas, or feedback that are surfaced by these groups.
I think it's important to fight the urge that we must be involved in (or at least have access to) every conversation on every part of this forum. It's not as though it's been announced that proposal reviews will now be run only in private groups.
Congrats to the Diversity in Swift work group on the launch! Excited for our community to continue to improve and grow.