Okay I get what you mean. Because of China's involvement in BRICS. That's a fair point.
I'm not sure what South Africa's stance on it is. I know they're definitely not in the consortium of African nations that unconditionally supports China. But I'm guessing they're probably keep their criticisms low key for dipomatic reasons the same as my own country (NZ). It's a pity.
I'd be more interested in their stance on other genocides in their own part of the world, but that's not something Western media has ever shown the slightest interest in.
Worth noting though that it was South Africa who hosted the recent African Union peace talks to attempt to end the incipient genocide in Ethiopia's Tigray region. So I don't think it's fair to claim they don't care about genocides.
And like I said, apartheid structures have a special relevance for them that is different to what China - or Ethiopia - are doing.