So?
He's a good skier. He has some nice tricks. Who cares if his arms are flailing? Flailing arms does not go away by just not doing it. Flailing arms go away with PRACTICE of EACH trick. Once you get comfortable with each trick, THEN you can add style to it. I bet if you watch some of Tom Wallisch's first backflips, they will have no style at all. But now they are ridiculously smooth. It all comes along with getting more comfortable with each trick you do. He might have just learned some of these tricks, he wont be perfect with them yet.