Maybe this guy is just a horrible rrrracist and couldn't handle strong people of color having a good time. An alternative scenario that I've seen in person is this gathering resulted in his patrons being treated poorly, probably some attitudinal response to his requests to cease and desist, and then he flew off the handle.

Where I live there used to be thriving nightlife on a certain street. Probably two dozen bars on a quarter mile strip. A few different factors caused the demise but long story short the clientele became more diverse, people got shot, women were raped and now its a ghost town. Funnily enough a bartender I knew said basically the impetus was bars hosting events like this one for a quick shot of revenue. They'd start coming back (not tipping or buying drinks) and poof, there goes your bar.