Also, while I"m no physiotherapist, it looks like musk’s shoulder mobility is hindered a bit. Maybe its the suit/shoulderpads, maybe he’s just really out of shape. Which is to say that he knew that he had to get his hand up over his head to get the gesture right. It’s significantly more effort than you’d do by accident.
To the person that made this gif: thank you for your service. You had to pour over far more footage of this nonsense than anybody should ever have to.