I think they don't want to ban Epic forever over this kind of spat because it sets a bad precedent and could turn other developers away from them.
Additionally I don't think it helps their public image and hurts the case they are making where they don't need regulation because they have fair rules (smacking someone out of the app store forever because they file a lawsuit wouldn't pass the smell test)
I believe most companies would refrain from engaging in new business with a customer who has pending litigation against them. Apple may not want to ban them and is just waiting until the appeal process has settled before reengaging with Epic under whatever terms are ultimately agreed upon between both parties and the courts.
