When this first occurred, I checked the SA press and there was no mention, whatsoever, as it's such a common and "normal" crime (for e.g. there was much more of an outcry recently when a three year old was murdered - been all over the press).
The criminal justice system in SA is by no means perfect, but I doubt that the would deliberately convict an innocent man of murder, or plotting to murder his wife, just to protect the tourist industry. All the people I've spoken to about this (south africans, english people etc. etc.) know that to go into a township, that late at night, is a ridiculously stupid thing to do. It's not like this is a new revelation "SA has problem with crime!" that is going to bring the tourist industry to its knees, so the country's doing anything they can to protect itself. That's just ridiculous.