Post-rotj AU is initially an Anakin's story. He was ready to die, but instead of this he survived and forced to live through the redemption. It's pretty uncommon for people to change sides so drastically and become a better person after being absolutely terrible for 20+ years and causing that much harm. And the trickiest thing that hating himself for it would get him back to the dark side.
Obi-Wan in this AU is also in pretty tricky position, but not because he did something deeply wrong. It because Force gave him a second chance he didn't asked for. It's not like he was prepared to die. He died. He sacrificed himself to save Luke. He was pretty content with this decision.
And Force gave him his life back.
He is glad that he can continue to educate Luke (btw it this AU Luke would have way more systemic jedi education; especially since Anakin would be even more strict that Obi-Wan about it). But overall he is not sure why Force brought him back. He joined rebels mostly because we wanted to be near Luke and initially was hesitant about joining any military operations. But Obi-Wan is very good at fighting, so he decided that he had to join military operations. And still he was really hesitant. Why did Force resurrected him? For teaching Luke? Yoda is still alive, and Obi-Wan was sure that he could teach Luke better. For being Rebel Alliance general? It sounds too shallow to be the will of the Force, and also Rebel Alliance already had successful generals.
(Darth Vader almost had a stroke when he found out that Obi-Wan is actually alive and fighting for Rebel Alliance).
We all know that Force brought Obi-Wan back to fuck Anakin.
At the end after talking with Ahsoka who also was kinda brought from dead under very weird circumstances, he decided that it's actually Vader who went against the will of the Force when he killed both of them, and Force just "fixed" this "mistake".