Shabbos: It's Over
The Exilarch will return as the Tractate concludes, but first we learn that "no one listened" to Rebbi's prohibition of kneading "because of the lenient ruling of R'Yose the son of R'Yehudah" (156a). Is this bad? So much of this tractate is concerned with building higher fences. Yet this breach in the fence will ensure that animals will not go hungry. I repeat, is this bad?
Then, abrubtly, the focus changes and several teachings suggest that astrology influences fate (156a). They are not exactly refuted; rather, the text insists that "celestial signs hold no sway over Israel" (156b); over others, however, the hold is firm. Israel averts its celestial destiny by performing mitzvot (e.g., feeding the hungry on Shabbos). The text does not so much connect the dots as put them all out in a cluster for the reader to connect.
Finally, in the last scene of this tractate the Exilarch is found in his bathtub, where he is measuring the water on Shabbas. It's not a problem, we learn, because he was merely "busying" himself-- "not measuring for any purpose" (157b).
I'll leave it to Reed Chopper to defend the Exilarch, if he indeed needs defending. It does seem that his role in these proceedings demands some explication.