Walker had a lot of good points in his rebuttal about how they made him and pointed him at targets. When he killed someone who had effectively surrendered to him, he crossed the you can't be Captain America line. Granted it was a terrorist, and that organization, though not that guy, had just killed his partner. Still you can't do that.
Walker's still a decorated veteran looking to serve his country, and those decorations were earned by following orders, and working to help his fellow soldier. He's a soldier. He'll behave like a soldier. He's had those rules beaten into him over and over again. He's been trained to lead men but also be part of a unit and do his part to achieve specific goals. He also seems more comfortable reporting to someone. This role will fit him much better as he'll be executing someone else's orders and he won't be the public media darling that even Steve struggled with.
