Elvis wasn't racist. He got his style because he grew up around black folk and mingled. However, he got all that "King" praise for being a white guy doing black things. That rightfully upset people. Now add 50/60/70 years to it, generations of people not knowing anything about him but still forced to know OF him, and you see how easy it is to get things skewed.
This isn't helped by the fact that while Elvis always gave black artists their flowers, his Estate does not. All of us only know Elvis via our parents memories and the actions of his Estate, and his Estate readily propogates the myth of him instead if the reality.
They could do wonders for his legacy by essentially re-telling his story, and his relationship with his black peers early on, genuinely. But they've already invested decades into this brand of white superiority.