SKYRIM BELONGS TO THE NORDS
I'm sorry, how exactly was Ulfric Stormcloak in the wrong...
The Hero of Kvatch is likely a Shezzarine, who are like, Lorkhan avatars that randomly crop up. The PCs achieving CHIM isn't "canon" but the powers that are attributed to it are extremely reminiscent of the players abilities.
What's more the very concept of CHIM is that you realize the world isn't real. Its a "dream". If you realize the world is a dream you either A. Wake up, or Zero Sum. You cease to exist. or B. You seize control of the dream like a lucid dreamer. This is the means through which Vivec, The Tribunal and Dagoth Ur got their own god like powers.
You the player, are already in the supreme state of CHIM. You are already aware of the unreality of the reality and have god like powers as a result.
Except the dragonborn had no way of mangling Talos. You need some kind of connection such as Heart of Lorkhan or the Staff of Sheogorath to mantle. At best he might be able to mantle Akatosh as supposedly the blood of Akatosh runs through his veins, but Akatosh would have to be removed from the pantheon first like Lorkhan and (sort of) Sheogorath.