The reigning Masuraou is strong but weak that's why he doesn't want to continue the tradition or probably because it's a waste of time and he did it on for fun when he was young and now is just pissed that he has to participate every year
The guy who hates the festival just happened to be standing around at the shrine dedicated for that festival and came down just in time to tell everyone to fuck off, even though the whole town is all about this shit?