- Just Hiding: It's not entirely out of the question that Michael survived and is just using Jack's body as a host.
- They Wasted a Perfectly Good Plot: Rowena agrees to become Michael's host after he threatens her friends and promises to spare them. It's ridiculously naive for a centuries-old witch like Rowena to not expect him to immediately go back on his word. It would have been far more believable for Rowena to perform a FaceHeel Turn if Michael had offered to resurrect Crowley, as Rowena had previously been shown to be ready to go war with Death over him.
YMMV / Supernatural S 14 E 14 Ouroboros