As you are surely aware, this book is not set in the present. It was first published in the United States back in 1986. Obviously, the racial situation in South Africa (Nelson Mandela still in prison, Apartheid, no one had ever heard of Jacob Zuma...) was radically different than today.
In that case, why complain about the use of the book today? The book still presents an accurate view of what South Africa was like during the time it was written. If we must stop using this book because it uses outdated language, then we must stop using Huck Finn, for example, because of its use of derogatory terms used for black people in the US at that time.