Originally posted by -K-M-Right, but Oblivion wasn't saying that peak CK was a mere aspect of his totality/power. He was referring to CK's original/base iteration: Mikaboshi. Hence the image of Mikaboshi he specifically opted to show us.
I disagree. He refered to mika and chaos king as the same person. He was still the chaos king underneath his attire. He just removed it during the story and that's when we saw his true face.
...He could have easily generated an image of CK-proper, if that is indeed who he was referencing. /shrug