You have to remember the fact that the reason that we are being seperated is because people were afraid. Now killing all the soldiers, won't change anything. Not to mention that it makes things worse.
I had Quickdraw simply knock out two guards and try to tell the other soldiers to get to safety and activated the beacon to call for help so they could get a rescue. And he was one of the people more willing to kill, because he was a soldier and is considered a terrorist by the government.
Also, this may sound like I have experience or something, but killing is always hard the first time, and with the ability these kids are doing it, with seemingly no remorse, its implying that they have killed many times in the past, giving the world reasons to be worried.