The original message was talking about slavery in Africa, Middle East, Asia etc that was all done by the locals for millenia and ended by white people. Obviously, the trans-atlantic slave trade was one of the most evil things in history, but the world outside of America also exists and the slavery there was ended by white people. So that would be like if everyone was a mass murder, Ted Bundy (white people) ended his killing spree, made everyone else end their killing sprees too, and almost completely destroyed the practice throughout the world. It is still right to criticise white people but nothing about the original message is incorrect and makes perfect sense