Whiteness was already known and not surprising considering the area's demographics. Not that relevant anyways here? By race on a per capita basis, whites and blacks are roughly equivalent in terms of spree killings overall. Further, this was a white guy killing presumably mostly whites (though his wife was Hispanic), also downplaying any particular racial motive. Beyond that, it was apparently an atheist shooting up a church, made particularly relevant with leftist atheists like that Wil Wheaton douche pretty much laughing at the shooting.
The reason black on black crime is notable is because beyond spree killings, they have an incredibly high murder rate. Black men aged 14-30 (or thereabouts), roughly 1% of the population, commit about a third of the murder. Myopia is not seeing that blacks live completely disconnected from reality and/or willfully ignorant to the many failures of their society, which values black in-group favoritism above all else.