Batman killing people is not unusual in film. Michael Keaton's Batman has no qualms about killing criminals, although it's usually played as dark comedy, like when he straps a bomb to a thug and smirks as he throws him off a ledge to his death.
More relevant is the Nolan Batman's perverse attitude towards killing - "I'm not going to kill you, but I don't have to save you (from this situation I engineered that will result in your death)". Bruce's attitude towards killing in those movies evolves from the League of Shadows test, where he refuses to execute the prisoner but then rebels and destroys their temple, assuredly killing many people including the man whose life he spared, to proclaiming some kind of moral lesson as he fights Ra's al Ghul long enough for him to die in the train accident, to when he finally just shoots at Talia's car until she crashes and dies but still refuses to actually just fucking shoot and kill her, even though there is clearly no moral difference.
In that film (Dark Knight Rises) Bruce is saved by the dreamlike happy ending where he carries a bomb out of town, then instead of dying in the explosion retires to a wife and kids. Affleck's Batman is a clear descendant of that character, without the cheap happy ending. He simply kept going and inevitably ended up at this point.
The article misleadingly refers to the Nolan Batman as "using ingenious methods to avoid killing", when what he's really doing is using ingenious reasoning to avoid admitting he's killed someone.