Change WordPress user roles and capabilities › Forums › Bug Reports › Some 'Admin Menu' items do not appear for Administrator role in Multisite › Reply To: Some 'Admin Menu' items do not appear for Administrator role in Multisite
‘manage_network_options’ is very critical capability in order to grant it to the single site administrators.
I see at the BuddyPress source code comments that “BuddyPress can now be activated
on individual sites”. BuddyPress activated for the single site (not network activated) will use single site capabilities and will be fully available to the single site admin. I suppose that this way of BuddyPress usage will be more suitable for you.