I think he's saying it may not be the best idea to send a group of men who often needed to be ruthless to survive their deployment. You don't fuck around and you don't give the other guys the benefit of the doubt if you want to get off the plane coming home standing upright.

Not to mention that in his most recent deployment, the "other guys" we're always trying to pass as civilians, so you get extra paranoid. You have to.

Anyway, those habits die slowly (if at all) and could end poorly for any civilians who trigger those old reflexes. But I'd be surprised if the enlisted are issued ammo for this.