Here's the thing.
Jericho is one of the few Superstars who realize they are getting older and are willing to put over younger talent. Jericho hasn't come back for money; he's in a successful band and has been fairly smart with his money. The reasons he's come back is because he still loves to entertain and wants to put over the next generation.
Think about it like this. What would Jericho have gained by winning over CM Punk? Not a damn thing, but what did CM Punk gain by beating Jericho? More noteriety for the Championship and further establishing Punk as a household name. What would Jericho have gained by beating Ziggy? Not a damn thing, but what happens when Ziggy beats Jericho? It puts a notch on his belt and further solidifies him as a future main eventer.
Jericho doesn't need to win to be super over with the fans and he knows it. He can lose and look dern good doing it.