Here’s an odd thing. When I’m on page wp-login.php, $bp->current_component appears to be empty at bp_init time, so bp_lockdown loops continuously (bp1.21).
You could always just use htpasswd to compel http authentication too. It’s a bit of a pain for users to have to log in to both the directory, and into buddypress, but it will give you the protection you need. Or you could just stick something into the theme to say that if the user isn’t logged in, they’re always redirected to the login / register page. I need something similar, so if I make any progress, I’ll post back here with it.
There’s wp-answers https://wordpress.org/extend/plugins/wp-answers/ too, for rating comments on wordpress posts. It’s a rough plugin that lurches into Spanish now and again, and doesn’t work on buddypress forums. However, it might offer a few more clues on how to get there.
The other thing to do would be to look for a buddypress plugin https://buddypress.org/extend/plugins/ for forums that added some metadata to forum posts.
Please do report back if you make any progress – I’ll be interested to hear how it goes.
And if I make progress with my mailman <-> forum plugin, I’ll let you know how I went about adding metadata to, and manipulating, forum posts
