If I believe my eyes, I see a bunker lip further up the hill, but not where the ball was. It was flat. Which begs the question.... when is the bunker no longer a bunker?
Is hitting off sand constitute a bunker on a shore course? If there is sand adjacent to a bunker, does that constitute being part of that bunker, or another nearby bunker? If you are over the wall on the 18th of Pebble, and down on the beach, are you in a bunker?
Bunkers need to be clearly defined. If you have 1,200 of them, and want them all in play, they need to be defined on the course, and not only on the rule sheet. If there is a lateral water hazard on the 11th hole, as stated on the rule sheet, is not the lateral hazard defined on the course?
Regardless, from watching that shot time and again from behind, and the photo of the crowd gathered in and around the bunker, I thought the ball was on sand but outside that particular bunker.
Also, you need to live with the decision from the local rule, but that doesn't make the rule a good rule.