I don't know the details of his contract but if he's in AEW on a full time basis then there's no rush.
Let him go through some other guys on the roster and then build up to the big clash with the champion.
We know it's going to happen at some point (i.e Punk going for the AEW championship) but AEW need to make use of Punk to enhance their entire roster.
Punk being on a card is already money, they don't need him in the title picture yet. So AEW should take advantage of this and build a strong line up which is what they are looking to do by having Punk take on one of their up and coming superstars.