Who is Mr. Buthelezi from The Kalahari Typing School for Men and what is their importance?

Mr. Buthelezi is a detective. He has opened a rival detective agency, the Satisfaction Guaranteed Detective Agency, across town. When Mma Ramotswe and Mma Makutsi visit, they discover that Mr. Buthelezi claims he was a member of the CID, and that he had once lived in New York. Questioning regarding these things, however, reveals them to be lies. Mr. Buthelezi advertises his new agency by claiming that only a man can be a detective, and that people should hire a man to do a man's job. Mma Ramotswe is upset by this claim, but she does nothing to fight back. In time, Mr. Buthelezi simply gives up.