Killing comes easy for Derek, but he's aware, abstractly, that it's not the same for everyone. It's never something he's thought too much about, expect when it directly impacted him - when his Tributes didn't want to fight to kill, when his opponents in the arena made winning easier because they hesitated. When Capitolites sneered at him or looked at him with fear.

But he thinks about it in a different way with Kurloz. Derek's never trusted anyone at his side except for Chuck - and he still doesn't, not really. He doesn't know if Kurloz will kill someone with his own hands when it comes down to it, and that's his main focus right now. There's a man with a gun at his side, holding it like he's planning on shooting the first thing that steps into his vision, and Derek doesn't know if he's counting on Kurloz using it if they run into trouble.

He doesn't know what affect it will have on Kurloz if he does, but Derek doesn't care about that right now. If he cares about it at all, it can't be in the middle of a fight. Nothing matters now but survival.

"Was trying to get everyone to the back of the train."

It's not a lie. He was, even if he'd planned on moving forward towards the fighting after he'd gotten out here.