|There are suprising few pictures of Frank|
The Seven Guns are Unstable and Dangerous
First off, let us look at the Seven Guns themselves. John Horus is (according to Tom Noir) paranoid and prone to overacting. A flashback seems to suggest John thinks he is superior to humans and invincible (which seemed to be supported with some dialogue he shares with Frank where talks about how he is the "hero"). To top it off, he kills the president and expects everyone to be fine with it. Kathryn Artemis openly supports John's actions and convinces her teammates to kill the government agents who are trying arrest John for his crimes. In a flashback, Artemis throws a knife at Frank with little provocation. Zoe Jump and Angel One do whatever Artemis tell her to. Tom Noir and Laura Torch (who is otherwise a nonentity due to dying prior to the story) altered Laura's weapon without anyone's supervision or approval. Then, they hide the fact the weapon is now powerful enough to fight John. Dominic Atlas Hyde's motivation to join the team is that he wants to be important and NOT for doing good. All of them are willing to resort to murder as a first choice. Only Angel One expresses concern for human life and even then it only happens once. None of them seem to even attempt to incapacitate their enemies and go straight for the kill. Add to all of that the fact they have extremely rare powers that most of the military is improperly equipped to fight. So, they are not only unstable, but have superpowers that allow them to cause even more damage.
Frank is Trying to Maintain Order
Frank seems to be mainly concerned with maintaining order. He never defies his superiors when it would suit him. For example, he has a special task force for fighting the Guns and doesn't use them until he gets the approval. Frank gives a speech to a chauffeur about how he wants to protect people. Frank formed the Seven Guns to fight corrupt cops and security firms. So, he wasn't being blind in his desire for order. In his final confrontation with John, he (rightfully) points out how the government exists to enforce the law and that "one man wearing a ... bucket on his head does not get to decide what laws are".
He is not Remorseless
Frank actually shows several times that isn't an emotionless monster. While in a car, Frank gives a speech about how he is "trying to protect what [he] love". It is implied he is talking about the American public. When he thinks that John defiled Laura's grave, he is visibly upset and yells at John about how he cared about her.
Black Summer trade paperback