I am not even remotely surprised to hear what is reported to have triggered the Charleston shooter:

From the dawn of time, men have attempted to protect their tribe's women from mating with outsiders. And women have socially ostracized men who pursued women outside the community. Black women hate it when black men date white women. Asian men hate it when Asian women date white men. And obviously, many white men are less than entirely enthusiastic about white women engaging in what they describe as "mudsharking" and "coalburning". I tend to doubt my Native American ancestors were particularly pleased when my grandmother quite literally married "off the reservation".

I'm not surprised that there has been such a vicious and violent reaction to the constant barrage of "ebony and ivory" in the media. The more the media pushes, and the more white girls respond to the propaganda by choosing black men over white men, the more extreme the reaction is likely to be. There is no inevitable "progress". Sooner or later, the pendulum always swings back.

The New York Times asked "who radicalized Dylann Roof?":

The pro-diversity crowd radicalized Dylann Roof. Sexual competition is pretty close to a zero-sum game, so every time a white girl decides to have sex with a black man, the seeds for another spurned Dylann Roof are planted. And those potentially violent seeds are watered every time BM-WF couples are advertised on television shows, on advertisements, and in the movies. Few of them will sprout, since the average man will simply write the girl off and find someone else, but the more that are planted, the more rage-filled killer omegas there will be.