How does Krakauer utilize the quotation from Chesterton that opens chapter 12? What examples from the McCandless saga demonstrate the relevance of this quotation?

The quote is:

"For children are innocent and love justice, while most of us are wicked and naturally prefer mercy."

I think that this has to do with Chris's father Walt.Chris found out about his father's infidelity to his mother. Chris felt he had lost his innocence when he discovered it. Chris felt his father deserved justice and not mercy. Some of the reasons that Chris separated from society had underlying reasons in serving his father justice.