Since when did "Boer" mean "white"? Or perhaps you think that the Boer wars fought by Britain in South Africa were against all "whites". In which case they would have to have shot themselves. - [link to en.wikipedia.org]

The "Boer" were the specific subset of white Europeans of Dutch descent who implemented apartheid . The song is from that period. You can find plenty of other songs glorifying violent periods of regional history sung all over the world.

Still, best he hadn't sung it and it brought legal action against him and won't be repeated.