Why executing young whites for killing useless old farts?

See for example https://en.wikipedia.org/wiki/Tiffany_Cole

It makes no sense to kill that lady. She is strong - she can rip the evil black hearts barehanded. Moreover, it will weaken the white race, if we execute white criminals. Instead we should set them free, but with a condition that they must kill as many niggers as possible to redeem themselves. I.e. ship them to Zimbabwe with some assault rifles, and make them recolonize Africa.

It worked for Australia.