Good analysis but it did not fully explore the depth of apartheid's role in rugby.  The Nats saw rugby firstly as a political tool to boost Afrikanerdom -- for many years the ratio of English speakers to Afrikaners in Springbok jerseys was one to three.
Even the famous Natal team which beat the All Blacks  did not result in English speakers being included -- many were bitter about that for the rest of their years.  As for scrumming down against anyone with crinkly hair...
This politicisation  made rugby an easy target for anti-apartheid activists, many outside the ANC, and they were so successful that the ANC rushed to join them.
In the early 1980s, even sporty young black, coloured and Indian youngsters who had access to "white" sports facilities could not and many would not use them.  If they persisted they risked the full wrath of black activists (and the contempt of radical whites).
These youngsters are now in their 50s and 60s, and the values they learnt then still linger.