They could make it epic and say it's a marooned Pius Dea warship, or a Celestial artifact. Or do it the smark (not a typo) way and says that the Makeb offensive is just to give to the Imperials hope.
The Republic 'won' at the end of the base game. The Empire could (and probably will) win Makeb, they need to stay in the race after all.
Wasn't the next planet leaked as Rakata Prime, anyway? Home of the dread masters.