Why does Jonas tell Asher not to play "Good Guys Bad Guys" anymore?

Gaining a memory of war deeply affects Jonas, who knows that everyone in his community is able to live a carefree, ordinary existence because of his suffering and the suffering of the past. It is for this reason that the behavior of Asher and the children in the play area nearly causes Jonas to break down. He understands that they do not understand that their imitation war game is cruel and representative of terrible suffering, but their inability to understand further isolates and frustrates him. The incident shows how their innocence of war makes playing at war possible, and it also highlights the lack of understanding that Asher and Fiona have about certain aspects of life as it used to be.