It is being heavily implied that Oda will offscreen. He is already telling us what will happen before showing. No way he is showing now what happened there.
SHs winning and taking over Egghead as you say would mean they potentially defeated an admiral and one of the Gorosei, there's no way that's getting off-screened lol
Again, the chapter ends with the marine fleet ARRIVING at Egghead, not leaving.