I guess its entirely possible the pilot had an onset of cardiac arrest on the approach, that made him lose control - but then he could have climbed out and had the full-on heart attack or stroke, just outside the aircraft.
The shock of a high G crash landing also just might have loosened some clot that then moved into a major heart or brain artery? I'm no medic, but "embolism" rings a bell. I believe it's not unknown to also have an elderly partner suffer a cardiac arrest, when they see their partner have a cardiac event.
Arterial embolism: MedlinePlus Medical Encyclopedia