An amazing photo to be sure. Who knows if that was the first, second or third initial shot? Seemed like Trump grabbed his ear at the first sound of fire.
Could have been the bullet that killed the supporter. Also looks low to have gone through Trump’s right ear. If the camera had a decent clock with timestamp, should be easy to determine which shot it was.
My take is that PDJT heard something - the first shot maybe or someone in the crowd yelling and turned his head.
Had he not done that he’d have been hit in the temple or the back of the head.
There are several people in the stands behind him who turned their heads towards the shooter just before he was hit.