Even in civilian life in the west, the police can try and kill a hostage-taker, and the result may be injury to the hostage, that's not the same as trying to kill the hostage. And Israel seems to trying much harder to avoid civilian casualties than, say, the United States in Iraq or Afghanistan, the Chinese Red Army during the Chinese civil war, the US or UK in WW2, Iran or Iraq when they were fighting each other, and compared to the Saudis in Yemen. And there is pretty clear evidence that Hamas does target non-combatants, AND Hamas is responsible for removing the protective shield that should apply to hospitals etc by using them as military assets.

And the document itself also says it does not define the law: "the interpretive Guidance is not and cannot be a text of a legally binding nature. only state agreements (treaties) or state practice followed out of a sense of legal obligation on a certain issue (custom) can produce binding law. "