Yeah, I can see far too many undesired results stemming from use of this device, particularly in as violent a society as South Africa is at the present time. Reprisals would very likely be taken on the woman by the rapist's brothers, cousins, friends, and fellow perpetrators and gang members, and those reprisals would quite likely be fatal in many cases.

You can't overcome this sort of thing by simply striking back at the lowest possible level of human behaviour. You have to reform a whole society gradually to make its general public more secure so that such violence lessens, and that means addressing all kinds of widespread financial and social issues, not just focusing on the specific individuals who commit violent acts. In a society where the average person is better educated, better housed, happier, and has more financial security than is presently the case in South Africa, the incidence of that sort of crime goes way down.

What's the number one cause of violent crime in the world?   Poverty. When people are desperate, they turn to desperate acts. That's why, for example, Somalia has become a haven for modern day piracy...it appears to be the best way to earn a living in that country at the present time, and millions of people there are in desperate poverty. I bet there's a huge amount of rape in Somalia too.