Harpooning halibut is always the safest way to deal with large halibut.   Notice where the harpoon head went through this fish.  Because of the boat being anchored in Cook Inlet Alaska, where the tides are drastic, the angle was difficult for the guide to place the harpoon head on the halibut's head.  If he had tried to miss the cheeks on the head, he could have cut the angler's line.  Sometimes you must harpoon where you can.