True. But it is also true that occupying force is responsible to establish order and prevent exactly such events. From the article it seems that it was provided for 30 minutes and it did have effect.
1907 Hague Convention
Article 43
The authority of the legitimate power having actually passed into the hands of the occupant, the latter shall take all steps in his power to re-establish and insure, as far as possible, public order and safety, while respecting, unless absolutely prevented, the laws in force in the country.
Article 56
The property of the communes, that of religious, charitable, and educational institutions, and those of arts and science, even when State property, shall be treated as private property. All seizure of, and destruction, or intentional damage done to such institutions, to historical monuments, works of art or science, is prohibited, and should be made the subject of proceedings.
Article 43
The authority of the legitimate power having actually passed into the hands of the occupant,...
The "authority of the legitimate power having actually passed into the hands of the occupant" occurs when the combat ends and the war is over.
Unlike a Hollywood movie, the words "The End" do not flash across the sky in wars in the Real World just because one statue of The Bad Guy is torn down in one public square near the hotel where the news media happens to be camped out.
U.S. forces are still rooting out and fighting Fedayeen and imported Islamist jihadists and still dying in the streets of Baghdad (a Marine was shot dead yesterday while guarding a hospital), the advance to Tikrit is in progress, the search for American POW's is still in progress, the battle by the Syrian border is still in progress and Northern Iraq still needs to been secured.
Once the war is over, then and only then, can you say that "legitimate power has actually passed into the hands of the occupant".
Until that time comes, U.S. forces will have their hands full waging and winning this war.
After U.S. forces no longer have a war to fight, then you can start waving your copy of the Hague Convention.