What happened in Knoxville was an appalling racist hate crime.
But it was not a riot. It was five thugs committing a very private crime.
Some of the other incidents were, but not the TN case.
BTW, this is not particularly new. When I lived in Sacramento 10 years ago, it was common knowledge, though never making the news media, that the last night of the state fair was “Beat Whitey night.”
With AZ now having no permit CC, beat whitey night at the AZ state fair would have a bad outcome for the would be beaters.