Varis was also far from father of the year material. He knew that swordmaster could kill his son and didn't do anything to stop it. He talks about Zenos being a monster later on but he created that monster with neglect, indifference, and zeal to just use him for Garlean's own ends.
I didn't really care for Zenos until EW and reading the Chronicle of Light story, but now I feel it's a shame he never got the chance to be someone else. Gaius did (but they admitted his living was a retcon), but Yotsuyu didn't and neither did Zenos. Not all villains need some sort of redemption. Ilberd and Thordan show us that. But EW showed that Zenos did take what Alisaie said to heart and I felt that sort of development deserved at least a chance to follow a different path.
We didn't see him dissolve into aether, so I do still have some small hope we might see his return.