A young white Afrikaner fights for the liberation of his people in an alternate history of reversed Apartheid.

"...the problem of racial discrimination needs to be hammered home, again? and again? and again, lest we forget."

Agreed, therefore best to do justice to the notion of tolerance and tell a compelling and original story one which has commercial appeal to a larger audience rather than a generic dime in a dozen?

Perhaps not exactly original, but the problem of racial discrimination needs to be hammered home, again... and again... and again, lest we forget. The role reversal in this concept underscores an inconvenient truth about homo sapiens, that no one race, no one people are immune from discriminating against another, from oppressing and exploiting the "other".

Whether there's a commercial audience for the theme is something else.

An interesting play on racial devices how ever the concept does't present an original idea at all.

Liberation stories of slavery on the basis of race have been told for thousands of years "Let my people go?".

The interest from the role reversal gimmick will ware itself out after about 10 min of screen time i.e once the opening image is established.
What about this story will keep the audience interested from that point to the end? How will it be different from the myriad of other similar if not identical stories?

My point is best to mention the MC's original and compelling inner as well as outer journey in this logline.

Hope this helps.