Everyone who is insisting Son didn't dive - take your Spurs-tinted glasses off and watch the video again carefully.
Son plants his right foot. Maguire plants his foot in front of Son's right foot, making minimal or no contact. Son then decides to not take another step with his left, instead throwing it backwards and diving to exaggerate the contact. It's absolutely clear simulation and a deserved booking.
Whether the initial contact was enough to be a penalty is up for debate, but Son earned the yellow card so it's hardly surprising the ref didn't give the penalty.
Son plants his right foot. Maguire plants his foot in front of Son's right foot, making minimal or no contact. Son then decides to not take another step with his left, instead throwing it backwards and diving to exaggerate the contact. It's absolutely clear simulation and a deserved booking.
Whether the initial contact was enough to be a penalty is up for debate, but Son earned the yellow card so it's hardly surprising the ref didn't give the penalty.