It made me think maybe he is talking about his parents going to heaven, or maybe them going to a better place. The title called Saturday really doesn't fit with what he is trying to say here which is interesting. The last sentence says "Spying their children aglow on earth with a meager heat, do flying parents cry like geese." Cry like geese is a weird comparison, I think if the author is talking about death he should use nice words and use comparisons that people find happy because everyone likes to think heaven is a good place, and that everyone is happy up there. It make it seem less scary fort those down here. Maybe he wasn't even talking about death but that is what I got from this part, especially from all the questions that are unanswered.
There were many other parts I liked about this book, all the stories were very interesting. It wasn't certain you could tell what time of his life it was, or even who exactly was in every story. I liked the overall message of the story the whole family thing was nice. I would have liked to see a better ending, but it did give a good message and I think it was well thought out and put together.