There's a vid of Jake Burton saying Shaun's the best thing to happen to snowboarding in years because of how he inspires young people just starting out. The vid is a couple years old. But no, someone as successful as Shaun would not be the reason why Snowboarding is dying, and if anything, he's they guy keeping it alive.
You should checkout some early Prince videos. He does what he wants because he's Prince and it helps him be who he wants to be.
When you become that famous or well known you can start doing dumb or tasteless things, partially because everyone watching you has stars in their eyes, you just do what you wanna do to be you, however dumb that is to other people (if it makes sense to you.) Anyway, look at some of the 80s rock stars with long pants and long hair. Did they destroy rock or did they help it evolve?