Yes and no. I think Selina writing to Sofia in Arkham is an important parallel to her first time there. Her brother was the only one to visit her. In fact, so much about her actions were a result of her losing Al. Now, here she is, she has burned, killed, and alienated pretty much all traces of her old life and family. Which is why they show her kind of catatonic when Dr Simp came in. But, now, here is a new family member reaching out to her. It goes with her goals of a new life.
It feels like setup because we are comic book nerds and have learned to expect that from everything.