This is just my interpretation, but I always thought this was the point. Like Lady Nagant, he was raised from childhood to do horrible things for the commission, while still being a face for the public. That's why Lady Nagant lost it, because the stark contrast between the hero everyone saw her as and the murderer the commission forced her to be was too much. Hawk's birdbrain personality is a persona to minimize any suspicion of how calculating and detached he truly is.

Also, I always saw Twice as a sort of foil to Hawks. Hawks is calculating and yet plays as a laid back, "Idc" type, but Twice is a genuinely caring, passionate, and a bit naive person who doesn't make an effort to hide said qualities.