The Additional privacy settings within buddypress seem to be acting a bit wonky in my install. Sites that have selected the top privacy setting (open to google) seem to work perfectly, but below that the privacy settings become too severe within the Buddypress listings (the privacy settings themselves still seem to work).
When "Block search engines" is selected, the site no longer appears in the Blog Directory, or on the Profile Page of the user. (I can still visit the site if I know the URL, and am logged out). The Activity from the site also does not appear in the Activity Stream.