You're spot on! While Oracle Enterprise Manager is an awesome product with a huge amount of potential uses, the licensing restrictions/intertwining is a problem for many organizations. It's something I honestly never really consider, as I am fortunate where those restrictions are covered with an ULA.
In this case, however, it would seem as though you do indeed need to have the Database Lifecycle Management Pack for Oracle Database licensed (And it would most likely need to be licensed for all targets), even though this is not explicitly mentioned in MOS note 2074168.1. Best log a service request with support or get in touch with your local sales/pre-sales contacts for clarity.
Hope this helps
Thanks for confirming Ian.