BuddyPress.org

So far the only method I have found to control activity stream entries is to work of bp_get_activity_type() having found the activity type – in this instance it’s joined_group you can simply wrap the loop that’s in /activity/entry.php with something like:

if ( 'joined_group' !== bp_get_activity_type()) :

this now means that the activity loop will only output an entry as long as it’s not of type joined_group.

It’s a bit of a crude approach and others may have a better solution.