Once again, why are people applying Occam's Razor to a work of fiction, which is consciously created to be surprising and to create unusual, unpredictable connections and story turns?
Look, if the writers want to say it's the actual SDF-1 Macross...they can.
If they want to say there were hundreds of Macross-Class battle cruisers made...they can.
If they want to say it's an illusion...they can.
If they want to say it's actually a completely different ship in disguise...they can.
If they want to say, it's Song Goku come to lay the Kamehameha on the Vajra and save the day...they can. (Well, maybe they can't say THAT, but only because of copyright issues.)
Now, admittedly, they have to make it at least semi-plausible, but still...they can say anything they want to. Because it's fiction.