I think that it's the older Sub-Zero for that very reason.
He's not wearing the same stuff that Sub-Zero was wearing in the first MKX comic, and Sub-Zero saying to Ermac (in the game) that his soul is "Not corrupted. Freed" also hints (IMO) at this being Bi-Han.
Noob Saibot was the embodiment of corruption, and maybe now his soul has been freed.
True, but that could be either brother since Noob Saibot = dead and resurrected Bi-Han or it could be Kuai, given that he also died.
The dead eyes don't point in favor of 1 or the other, IMO.
We have to look deeper than just the eyes.