Just thought of this theory and thinking it has some merit.
So don't have time to properly flesh this out now but we know one of Hoid's aliases is Topas, or bearer of the first gem. We also know he's no longer human via WoB.
Perhaps Hoid was adjusted, a la Spook, at the Shattering as a final act by Adonalsium? Might be a good spot for Ado to hide its cognitive shadow as well.
Also a good spot to bring a Spren along while worldhopping back to Era 2 Scadrial!
Might this also explain Hoid's inability to harm on the Physical plane?
Find out next time on... DragonSteel Z