That's fair, but it seems like a fine line when we've shown in the past that she and her crew are willing to kill or grievously injure people just doing their job. King Shark just chewed the head off a guy just sitting at his desk.I think more the point was Harley doesn't follow "the rules," she goes by her own code. Yeah, she's maimed guards like the ones in Arkham or the improv group at the Gotham Mint bar mitzvah, but she'll only kill or help kill those who deserve it. Henchmen. Corrupt bankers. She has her own morality, and doing something like killing children isn't in her wheelhouse nor is sacrificing her friends in a fight.
And that's not even getting into that she'll apparently go to bat for a "friend" even if that friend tries to kill her or doesn't really seem to care about her. Did she bat an eye at Frank eating a kid and his whole family?
I guess these are the kind of issues you get into making a show about a villain while still trying to keep them likeable enough to not hate.