What is your answer for when someone's trying to kill you while hiding behind civilians?
My response is: that's what snipers are for. If you can't get a clean shot right away, then you patiently wait until the hostage taker makes a mistake and you seize the opportunity to get the hostage back safely.
There are many possible ways to eliminate a threat hiding behind a hostage. Shooting through the hostage in order to kill the hostage-taker, or killing everything that moves in the area where you suspect the hostage taker might be hiding, are two possibilities, neither of which are acceptable if you value the life of the hostage.
How long would an Israeli sniper stay undiscovered or alive in the crowded confines of Gaza?
Sounds such a splendid idea when safe in the confines or your office or home typing at a keyboard but absolutely impossible in the real world of Gaza/Israel.
The reason I brought up the book
Black Hawk Down: A Story of Modern War is because the raid to free hostages in Gaza last week brought it to mind. Over 200 Somalis were killed and more than 700 wounded in the Battle of Mogadishu as the American forces first raided a meeting of Mohammed Farah Aidid's lieutenants and then fought to get themselves and their wounded comrades to safety.
The book illustrates what I think you're getting at, that it's impossible to avoid civilian casualties when a firefight breaks out in a crowded area. Hell, just looking at all the gun violence in America illustrates the same point. Bullets go flying in all directions, including through walls, when people hyped up on adrenaline start shooting.
But my point stands: shooting through a hostage in order to kill the hostage-taker, or killing everything that moves in the area where you suspect the hostage taker might be hiding, are two possible ways to eliminate the threat the hostage taker poses. Neither option is acceptable if you value the life of the hostage or want to avoid killing innocents.