Heh ... They are actually ROMULAN SPIES that have infiltrated Star Fleet.Why not? They are military officers and it is their duty to report their successes and their failures. And, with the resources of the Federation and Starfleet, Commorode Oh could locate the La Sirena and send that information to Narek.
What makes you think they have any kind of morals or a sense of duty beyond obtaining their own set goals?