Keeper of the Superfluous Es!

Another for the minority viewpoint - I do think Snape might have played Quidditch. "Jealous of James' Quidditch skills," I thought, would be a more likely assumption to make about someone who played, but who played less well than James. A non-Quidditch player would be less likely to care. And in terms of being ref for that match - usually, referees have some experience playing the sport.