While I know that there are defiantly some real racists this bad still in the world, I can't help but remember that there are people who will false flag this type of thing because of their underpants gnome plan:
1. Giant Race Riots
3. Marxist Utopia
The whole leaving one witness alive to recount the horrible things both done and said could be a way of making sure that the "right" people are officially blamed. The moment this waste of oxygen is identified the his "social media" needs to be locked down tight before it's sanitized no matter which of these scenarios it turns out to be.
Since the original post the looneytoon has been both identified and caught. Social media equivalent of wall scrawling looks like a genuine white supremacist with a healthy dose of crazy and psychotropics mixed in. The above post was wrong on it's speculation.