Do you believe his jailors deserved to go to jail? What about his prosecutors? The results of the Truth and Reconciliation Commission clearly indicate evilness of the apartheid regime and those in control of it. That Mandela's response when gaining power was not one of retribution, revenge, and bloodshed clearly indicates in my mind that his was a principled, moral mind and that he clearly did not deserve to go to jail.
I figured the 70k number came from crime counts or something similar, since it's easy to build up non-negligible numbers pretty easily when 50 people are murdered in your country per day, which is the case in South Africa.
But individual crimes, even crimes partially or wholly racially motivated, do not make for a race war or genocide.