They stuck to their rules as described in the rules sheets they distributed to every player. Because this is a likeable guy and he's on the 72nd hole of a major championship, you want them to waver and say "oh, we didn't mean THAT particular bunker?" I'm betting other pros hit it in bunkers where gallery members had walked, they just didn't do it in front of a handful of cameras and several million people with the title on the line.
Give the PGA some credit for sticking to their guns and not giving in to the throngs of people yelling "Let him play."
And the "run a tournament as well as they teach golf" comment is rather ridiculous.