At the risk of sounding insensitive, this does remind me of Gov Cuomo's 'you don't need more than 7 shots' law. Obviously police aren't subject to this. Maybe if they had to obey the same rules as citizens that eighth shot wouldn't have happened.
Ok, sarcasm off, that officer walked in to the worst possible scenario. Unknown environment, active threat, multiple innocents.
Taking a head shot under stress on a moving target is a bad idea. If you try and miss the bad guy is going to open fire at you or the hostage. Even if you hit you might not drop him. Might just crease him, nick an ear, blow out a few teeth or cheek. They are still in the fight.
And what then? You are getting fired at.
Think you can still put precision in to your rounds when muzzleflash and noise, not to mention supersonic projectiles, are coming your way at 7 or 10 feet? I'm good but I'm not a rock.
A handgun is not a precision instrument under the best of circumstances.
If it were a loved one and I had a clear shot I'd take it. But a stranger? Man, I don't know. If that person testified that they felt their life were in danger by my actions of firing at their captor, in my state, I'd be tried (at best) with assault with a deadly weapon, and spend a long time indoors. In a shoot in IL, if you are intervening, YOUR mindset isn't what comes in to play. It is the person you were defending. If they didn't feel their life was in immediate danger, you are screwed.