After Finny dies, the war truly comes to Devon. Before, while there was heightened military presence around the campus, Gene remained separate from the reality of war. Even Leper's experience is somewhat surreal to him, because Leper's psychological issues keep him from fully communicating his horrors to Gene. However, after Finny's funeral, Gene stands at his window and witnesses Jeeps rolling across the fields. He describes the Far Commons, and how he "watched the war moving in to occupy it." In this novel, Finny represents peace for Gene and the school at large. With his death, peace deserts the campus, leaving Gene to face the true knowledge of war.
Gene explains why he thinks no one accuses him.
None of them ever accused me of being responsible for ... what had happened to Phineas, either because they could not believe it or else because they could not understand it. I would have talked about that, but they would not, and I would not talk about Phineas in any other way.
So Gene says he's willing to talk about Finny's death, but only with regards to his own role in it. Although the boys earlier staged a mock trial blaming Gene for Finny's fall from the tree, perhaps the reality of Finny's death is too much for them, & they cannot begin to understand how Gene may have played a role in it. Also, even if other boys felt Gene was responsible, what would telling him do? There wouldn't be a real trial, & unless they were just looking for closure for themselves, there wouldn't be much point. In fact, Gene himself says there's no reason to discuss what can't be changed.
Gene represented Devon school to fire shots on Finny, lead him through a secret passage into a freedom wonder land. Finny was dead long ago but now reborn as a freeman. However, i suppose Gene is responsible of firing too many shots on the same spots that causes Finny heartache and crippled. Should Gene demonstrate one more miracle to heal Finny in order to convince everyone she is truly an angel.