Ramirez scoffed as Gunny called him a nurse before he got into position near a tree and aimed his ma5 down range, judging who he was going to be firing at before Sgt Knight shot, he decided that decommissioning the kid would be the best way to go. 

Although Ramirez hated the insurrectionist movement he wasn't going to kill a kid and to avoid the kid killing any of his comrades he decided that once the shooting started he would incapacitate the kid before turning his attention to the three men speaking out front. 

Once Sgt Knight shot, he did just that, shooting the kid in the knee with his first shot before turning the gun on the three guards.