When I was there I never talked to a single British or Afrikaans that I would ever describe as white supremacist, or even racist. Everyone of them at some point voted ANC, mostly in Mandela‘s time.
However, going through Durban, I saw the dead remains of Namibian immigrants who were just necklaced in a almost 100% black area. Almost all the murder or violence there is white aggressors. I was forced out of Escort one day for being white. And our car was attacked by bottles and rocks in Mooi River, very presumably because we were the only white people around, although I didn’t ask specifically.
Slandering someone you don’t know as white supremacist because they are a South African white, is really messed up.