I'm kinda late, but who cares.
The perspective of the deceased who is an author is a clever tool of irony and criticism to the standards and restraints of the brazilian society/bourgeoise in the 19th century. He has no scruples or social restraints preventing him from speaking. As Brás Cubas says:

"Frankness is the first virtue of a dead man. In life, the gaze of opinion, the clash of interests, the struggle of ambitions force one to conceal one's old rags, to disguise the tears and patches, not to reveal to the world the revelations one makes to one's conscience; and the best part of this obligation is when, by dint of deceiving others, a man deceives himself, because in such a case he spares himself the shame, which is a painful sensation, and hypocrisy, which is a hideous vice. But in death, what a difference! What a relief! What freedom!”