"It was a generous thing." Was it? Who is speaking here? In what tone?

Henry, the youth, is speaking, and no his actions are not generous. Wilson has asked Henry to return the packet of letters he gave him to send his family in case he died in battle. They are Wilson's letters, and Henry should have returned them without question.

He had been slow in the act of producing the packet because during it he had been trying to invent a remarkable comment on the affair. He could conjure up nothing of sufficient point. He was compelled to allow his friend to escape unmolested with his packet. And for this he took unto himself considerable credit. It was a generous thing.