The reunion with their son is such a core part of the story. It really deserved a longer a...

It makes sense that it was so short. Their son is the macguffin. A macguffin is a literary term for an object or person that the main character desires and is essentially the driving force of their actions. But ultimately is not important for the plot's development. This story could have happened whether their son lived or died; regardless if Sooha conceived a child or not. The plot would have continued forward. Therefore, their son is the macguffin in the title.