I’d agree that’s primarily why they hated him, but they literally blacked up and made the abuse racist in its nature. He’s spoken before about getting racist abuse in the sport from the age of 8. As he stood out, and he was largely better than most of the rich white kids who he was competing with. His skin colour was an easy target.
If virtually the only black bloke in the sport is getting the bird for now speaking out about racism, given the current climate and the fact that racism in general is being debated, then it does little to dispel the notion that it’s still an issue.