not sure if it appropriated. I do understand your point. Dancing a haka before a rugby match seems to not just be isolated to these guys. http://en.wikipedia.org/wiki/New_Zealand#Sports

I'm not from New Zealand, so I don't know. Thankfully, it doesn't seem to be something done by a mascot before a game, but a group display as it's done traditionally, and from what I know this would be the time to dance a haka.