Why did the narrator recall his Uncle Podger?

In Chapter Three, the men are at the pub compiling a list of what they need to pack. Harris volunteers to write out the list, and J. compares him for the reader to his Uncle Podger, who always volunteers to help others but bungles the job because he is so accident-prone. Further, Uncle Podger ends up causing more work for everyone else because of his general incompetence. To illustrate his point, J. tells a lengthy story about how Uncle Podger once caused chaos for his entire household when trying to complete the simple task of hammering a nail into the wall.