I didn't see the race today, and I don't want to speak about this particular instance, but I do share the original poster's general sense of racing etiquette as the leader (and presumptive winner) approaches the finish line. I understand that others feel differently, and I understand that it's not uncommon for the leaders (and presumptive winners) of triathons to slow down, wave, high-five spectators, and so on, but I would much rather see the kind of finish that Ritz had when he won by an even bigger margin over Webb and Hall in 2000. To me, a hard finish without celebration seems more modest and more respectful of the competition. I suspect that the different behaviors, and different responses to those behaviors, are largely reflective of personality types; I identify with, and respond much more favorably to, introverted, shy individuals who seem rather uncomfortable with or ambivalent about competition and the adulation that often accompanies competitive success, while others love to see and feel part of a victory celebration.
As for looking back at every turn to check one's lead, I used to do that a lot, even when I had huge leads. For me, that was not based on any desire to bask in the glory of being way out in front; rather, I was terrified that someone would sneak up on me and race by me at the end, and I wanted to make sure that I had as much information as possible about where my nearest competitors were.