I think the issue/confusion here may lie in thinking of Yugol as an antagonist whereas it is more of a constant of the universe.
It cannot be reasoned with, it cannot be killed, it cannot be undone. It is the essence of nothingness.
In contrast, Ch’thon is a primordial elder god, the progenitor betrayed by his children, torn asunder and cast into the abyss. Incapable of ever truly dying, he yearns for the return of what was taken. His return to the mortal plane would herald a reckoning never before seen.