......the Breaker of Horses and Men, not such a great guy after being Dunyain mind fucked.
Cnaiür fit thematically into this book for that reason; he's the polar opposite of Anasûrimbor Koringhus in many regards. They both demonstrate how damnation relates to free will vs. determinism. Cnaiür was likely "born to damnation" due his culture, no matter what - but he wouldn't be damned to that extreme degree if Moenghus didn't enter his life.
Koringhus's story, by contrast, demonstrates that a form of "free will" does exist in Eärwa (which is absolutely a fatalistic universe,
not deterministic). Koringhus was also born to damnation, like all Dûnyain, and was damned by the circumstances - by the facts of life that he couldn't control. But in the rare moments when he
did have control, he made the righteous choice, such as saving his defective son from euthanasia. This, along with his epiphany of "All is One", leads to him finding the Absolute (the God of Gods) and being no longer damned.
Maybe things would've been different if Cnaiür had stumbled upon Mimara or found Taoism at an earlier point - but I really doubt it. His death-worshipping culture and violent temper would've damned him anyway, Moenghus or no.