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There's a lot you can do with the memory of a dead child. You can sanctify him, build a shrine to that boy in your heart. Ditch the flaws and edges that made him who he was, those are not needed anymore. He's no longer a person, just the idea of one, why not make it a perfect one? It'd be nicer to him, to only speak about the good stuff and forget the bad and grey.
You can also exonerate yourself through him, he's not going to mind. It's always a tragedy for one to be lost so young, the living are grieving enough as they are. Why turn this tragedy into a blame game? You can just push it onto him, he won't feel bad about it. He won't feel anything at all, not anymore.
Before you judge this, think about it. The grieving father is inconsolable, a pain so indescribable nothing can make it right. Would you point out his shortcomings at this trying time? Of course not! It's best to alleviate his guilt. If the kid was alive, well then it'd be different. The awful victim blaming of a kid trying to do good. But there's no victim here, just a corpse. You can share the responsibility with him.
A dead kid is an awful, unholy thing, but it is also a convenient one. Certainly, much more convenient than a living man, with human flaws and desperate for justice. Graves are perfect for burying things, but ghosts are a wrathful force. They'll haunt the narrative, they'll haunt your dreams and if you'd be so unlucky to offend them, they'll hunt you for sport.