Because both the Abyss and Stars were similarly eroded by Chaos, it was just that the erosion had not yet reached the critical point of life and death,
but once infected and eroded by Chaos, it would irreversibly lead to ultimate destruction.
Omniscience needed the Abyss and Stars to expand itself and enhance its tolerance to Chaos, but didn't the Stars and Abyss need to expand as well?
Therefore, the Abyss and Stars proceeded with their predesigned plan to plunder the Omniscient Authority, attempting to become a trinity of new deities, knowing that there was a probability of losing the gamble, especially since an early confrontation increased that probability significantly.
So after they merged with the Sons of the Abyss, they proposed to Lin Xun to go to his home world to search for the Way of Coexistence with Disorder.