Given the perverse logic that a lot of these SJWs apply, it's possible he simply wanted another ethnic group to be blamed and retaliated against, even without cause. Just getting even for hangings that occurred 150 years ago. Who he hated would be immaterial as long as retaliation and retribution was extracted, regardless of whether it was properly directed. (No, it doesn't make sense logically, but since when does that matter?)
OK so the guy burns his own church, perpatrates a false flag hate crime where he uses a violent distructive act to exact political gain and it's not terrorism even though this is a text book example of terrorism. I also don't see why faking a hate crime to encourage more hatred isn't considered a hate crime when the only motivation for the act is to breed more hatred.