Thanks for your thoughts, this is why I didn’t want to go into category permissions too much at first with that everyone change 
I think a lot of what you say here could simply be made impossible, I’ve already been working on some preliminary systems here with ACLs and a nicer permission UI on our kanban plugin that we are developing, here is an example, we intend to change the category permissions to use this eventually:
There are several rules involved here, like it’s impossible to give anonymous users Manager permissions for a kanban board and so on, and even supports mandatory permissions, like Admins can always manage a board.
We would make it so you can’t add anonymous users when the forum is login required.
Again, another validation/restriction we can add.
We could add validations/warnings for this kind of thing too.
This is what I want to avoid, these kind of implicit permissions that are everywhere in Discourse, rather than having logged in users + anonymous users explicitly always setup for a category if it’s public/not read restricted.
Anyway, for now I don’t want to get too deep into this, there’s a bit of a way to go before I deal with categories. But I do agree the OP is a bug that needs to be fixed in the interim, so I will still do this.