Chris Jericho might have very recently decided to join AEW and may not have thought about it a few weeks back. According to Dave Meltzer, from the Wrestling Observer Radio, he talked to the WWE a few weeks back.
We only found out recently that Jericho will be working for All Elite Wrestling. AEW recently held a rally called Double or Nothing recently in which they announced that Jericho will be part of the roster. In a video that Jericho released after that rally, he said that he will be in for a “long haul” with AEW. He said that he is going to be “changing the universe” with All Elite Wrestling. Jericho made it clear that he simply wants to try out new things and he isn’t joining AEW for the money, as he already has plenty of it.
Due to Jericho’s move to AEW, he was put under the Alumni section of the WWE.com
It appears that the deal with AEW is not an exclusive one. He may still be allowed to work with NJPW but only his contract seems to be the special one that allows it. All other wrestlers that signed with AEW must only work for AEW. NJPW officials are really interested in keeping Jericho and using him for future matches if some sources are to be believed.