My guess is this was about to come out and this particular rich white guy didn't want to deal with the hassle before cashing out over $1B. The email itself isn't overtly racist, though some of the typo/Freudian slips are pretty funny (White Trashers, instead of white attended Thrashers games) but it does delve in spots to focusing on the stereotypical differences between white people and non-white people, instead of focusing on his market. The guys is in so many ways (subconsciously) saying that he wants the black fans who are showing up to be replaced by higher spending white fans. That is not something you want the leader of your organization thinking. Instead, he should have focused on the problem of selling more season tickets to the people that show up at games. I.e. discount family tickets (2 adults and two kids tickets, or a half price kids ticket with every adult ticket, etc.)
It he wants to change the game ops to be more mainstream, then he should say that instead of implying that it should be lightened up. He probably doesn't realize that most mainstream acts these days aren't white.
Lastly, his market is not everyone else's market. He is benchmarking like all execs do, but he fails to realize what make his market unique is an opportunity and not necessarily a challenge. If the perception that his arena isn't safe, then address that, by hiring more visible security, integrate with arena parking and transit, ally with the neighboring entertainment district association or form one is one doesn't exist to impress that a hawk game night is a safe no hassle experience to those whose sensibilities might feel otherwise.
That is how a businessman addresses a demo problem.