The terrorists broke Geneva Convention Protocol by placing weapons into a religious building. Because of this, our military had the right to shoot to kill any all combatants, no matter the reasons. They broke protocol and now they have to face the consequences. It's like a person who drives without a license and has an accident with another vehicle. He is automatically at fault for the accident because he shouldn't have been driving in the first place so that the accident wouldn't have taken place if he were not on the road. The same priniciple applies here. Since they were illegally putting weapons into a house of worship, they had to face the consequences for breaking Geneva Convention Protocol. If they had not brought weapons into the mosque, there would have been no reason for our military to go into that mosque, and therefore no terrorists would have been killed, nor would the mosque has sustained any damage from our military. They would have been non-combatants....end of story.
So what's to stop you from killing an uninsured motorist who gets into an accident with you?
"But your honor, he shouldn't have been on the road in the first place!"
Your argument in regards to the Geneva Conventions or our Laws of Land Warfare are on the same level.
Both FM 27-10 and the Geneva Conventions are available online - you might want to avail yourself of the opportunity of reading them before pursuing your line of reasoning any further.