BuddyPress.org

This may help (thanks to Boone). It’s written for BP 1.1.3 which has the same problem with private posts/comments in the site wide activity stream. If you try this solution let us know if works on your BP 1.2 install.

https://buddypress.org/forums/topic/hidden-blog-posts-from-private-blogs-in-sidewide-activity-stream#post-32757