@Ryuksgelus:
Now you're talking from the readers perspective where we get an overview of everything going on. He has no idea that Kizaru is aiming a shot at Luffy. All he sees are people fatally injured but alive on the battlefield who can be saved and instead of doing so his bosses want to pursue an objective that is just adding more and more casualities.
They really havent changed their objective, they've just added kill Luffy to that list.
They always intended to kill all the Whitebeard pirates. This was what they knew would happen when they stepped on the battlfield, it wasnt let's kill Whitebeard and then have some ice tea.
Nothing moronic about realizing the marines have their current priorities entirely fucked up. Stretching your lines thin to fight on two fronts(one necessary, one optional) is a classic military blunder that we know is obviously going to cost them.
They've cut of the head, but most of the enemies commanders and the bulk of their army still remains but they are disoriented, the commanders are weakend and the men have lost the will to fight back and could very well be beaten if you strike before they reorganize themselves. It's perfectly sound to try it, if they're beaten back then they should and probably would've left it alone but not even trying capitalizing on such an opportunity would just cost them more in the long run.
Especialy if your reason for not doing so is "because people are dying in this war". I mean what does he think war is, there are stories during the napoleonic wars about soldiers sitting among their dying comrades and eating their rations before the next charge. War is fucking hell, people will die, even if they pull out all troops and take those troops to the doctor the odds are that their 18th century medical science isnt going to be able to save a third of them.
All Coby is spouting is naive idealism with absolutly no anchoring in military strategy.
@Ryuksgelus:
Is the lack of significant blood and gore really blind you to the situation where thousands of marine soldiers are being left to die?
Like i said earlier, in a field battle up to a third of their fighting force can be sacrificed to ensure that their objective is fullfilled. All these men are career soldiers and should know this by heart. Except Coby who just joined.
Leaving Teach to Garp&Sengoku is just a huge gamble as even against Shiki they destroyed half the city.
They along with Tsuru are both the most experienced marines around, and if they think they can handle two fronts then i'm gonna take their word for it over a private who's never even set foot on a battle field in his life.
Honestly why cant he leave the command decisions to those who have actualy been in battle before.
I mean even Tashigi comments they're going too far, its nowhere close to naive naruto style child idealism, where he says spouts total impractical nonsense.
Coby's words at the end are just common sense, not pacifist idealistic bullshit.
Dude that's all there is to it, he's not making any stragetic suggestions or saying lets focus on Teach he's the real threat.
He's just screaming stop the war people are getting hurt and mucking up the mission.