The following is from the official Twitter account of John Laurinaitis:
And to those wondering why Brodus didn't debut tonight, I have my reasons. He will debut next week, I promise. Why would I lie? #Raw
— John Laurinaitis (@WWERawGM) January 3, 2012
As you can see, Clay's delayed debut on WWE Raw Supershow is an angle. I'm not sure when it turned into an angle but clearly it's part of Laurinaitis' gimmick.