Nadal is not a Grand Slam umpire.
No professional tennis umpires are professional tennis players. If you are a World Tour player, then you are a professional tennis player. All Grand Slam champions are World Tour players. All Grand Slam umpires are professional tennis umpires. Nadal is a World Tour player or a Grand Slam champion
∀x (ProfessionalTennisUmpire(x) → ¬ProfessionalTennisPlayer(x)) ∀x (WorldTourPlayer(x) → ProfessionalTennisPlayer(x)) ∀x (GrandSlamChampion(x) → WorldTourPlayer(x)) ∀x (GrandSlamUmpire(x) → ProfessionalTennisUmpire(x)) WorldTourPlayer(nadal) ∨ GrandSlamChampion(nadal)