Even if this were true, it wouldn’t matter that much. Because Orks are psychic, if enough of them believe that the Lost Primarchs are Mork and Gork then they become Mork and Gork for all intents and purposes.
Unless a Primarch is now suddenly psychically strong enough to resist being transmuted by the collective psychic pressure of all Orks across the entire galaxy.
Even if this were true, it wouldn’t matter that much. Because Orks are psychic, if enough of them believe that the Lost Primarchs are Mork and Gork then they become Mork and Gork for all intents and purposes.
Unless a Primarch is now suddenly psychically strong enough to resist being transmuted by the collective psychic pressure of all Orks across the entire galaxy.