Wait wait wait, are you telling me that Chris Jericho has to win the Royal Rumble to have a legitiment challenge to CM Punk for the title...really? He's Chris freaking Jericho he could come back an hour before wrestlemania went on the air and could be made a legitiment contender for the title. Sheamus on he other hand hasn't really done anything to put him in #1 cotender position over the likes of Randy Orton, Henry, Show, etc etc. Sheamus needed the Royal Rumble, Jericho didn't.
Jericho comes out tomorrow says "Punk you never eliminated me, you knew you couldn't beat me so you got me taken out of the match blah blah" to which Punk makes some witty comback they get interrupted by The Miz who says he should be #1 contender because he was the last left in the chamber, you have Johnny Ace come out make a #1 contenders match-up between The Miz and Jericho, Jericho wins possible with some R-Truth coming after Miz, and presto CM Punk vs Chris Jericho at wrestlemania is set. Sheamus couldn't be set up nearly as easily.
Side note--Why is it every time I went to type Chris Jericho when typing this I instead typed Christ Jericho and had to edit it