That is very true. But that the Panther's arena is actually in Sunrise, Florida - pretty far from the tourist spots. If a Las Vegas team had an area in walking distance from the strip and your choice for the evening was between Carrot Top, Celine Dion and an NHL game I think they could take advantage of the tourists. Also, the hope would probably be that there would be that people would gamble on the game and then go watch it.
Again, I think it's a horrible idea, but (if the rumour is true) that is probably what bettman is thinking.
Tourists go to Vegas to see Celine Dion, Carrot Top, Penn and Teller, etc. along with gambling. They don't go to see a hockey game. Even if they do come from Detroit, or Toronto, or wherever to see their team play Vegas, they're not going to be buying $150 Las Vegas Regrets jerseys, and $20 hats, or the other merchandise.