Since I can’t comment, I’ll post it here: to view (or comment on) a password-protected post, we need to know the password with which it was published, not our password. Ergo, unless we know your password, we’re left wondering what you said.

(Unless we have root access to the database, in which case we could circumvent it, but not everyone has that luxury. )

I think categories is a permission-based thing. I’m not sure it’s the best way to split things up by user. There are a few other methods, I just need to spend more time experimenting with them.