Both of them and neither of them. The article is correct in that leadership is required and neither has shown leadership to date. They each bear some responsibility. But to think a president can obliterate hate, intolerance, or prejudice is naïve. People keep this alive and will do so regardless of a president. Unfortunately, it is a part of the human condition.
I'm inclined to agree with ninja. It is intrinsic to human nature and there's no magic cure to it. Consider how long we've been living in cities - since 11,500-9,500 years ago. Despite that huge (In human terms) period of time, mankind is still not adapted to sprawling metropolis'. This is readily apparent by the higher rates of depression, drug use, violence/crime, domestic issues, and more. So the idea that 70 years of actively trying to stop people from being tribalistic is going to do much, if anything, seem naïve to me. Could presidents do more? Sure, I guess; but at the same time, what can they do? There's constant crisis' and the public demands that each outrage be answered. The best they can hope for is to say the right thing, and hope it's at the right time.