Deep in the trench, Pontus ultimately acknowledged this assertion.
However, what truly convinced the Primordial Sea God wasn't because of Zeus's previous actions altering history and inverting the truth, nor the ludicrous reason of believing that the Great Serpent from the Abyss was inherently trustworthy.
This matter was only good for a laugh; for real judgment, one obviously needed more practical reasons.
And for Pontus, the most practical reason was undoubtedly Zeus's character and his own longing for power.
The latter goes without saying, throughout the Second Epoch, the Sea Gods fought amongst themselves only to unify the sea and to break the upper limits of a True God's power.
His so-called withdrawal from the world was actually because he was frightened by the Sun bathed in the sea, realizing the slim chance of defeating the God of the Ocean, rather than truly seeing through the vanity of life.
As for the former... that's just Zeus's consistent problem with style.