Removing BuddyPress admin bar from all sites except sub-domain

I have a working WPMU site which only had the default blog enabled. I've since created another blog, installed and activated BuddyPress, added the blog ID to the wp-config.php file and have confirmed that BuddyPress appears only on this second blog. My first blog still sports the default kubrik theme. After doing this I notice that the BuddyPress admin bar appears on both websites. I don't want this and instead only want the admin bar to appear on the BuddyPress site. I added the

define ( 'BP_DISABLE_ADMIN_BAR', true );

entry to the wp-config.php file but it also removed the admin bar from the BuddyPress. Is it not possible to have the admin bar to ONLY appear on the BuddyPress site? I only want the admin bar to appear on the BuddyPress site.

Am I missing something simple? Any responses appreciated.