This made me think of how Philip used that same phrase when he was trying to explain why he saved Martha. Elizabeth was talking about him liking her--iow, he was putting his personal desires above the greater good. He insisted that she was a human being. I think that's the term he used. Iow, saying that she ought to be treated like a human being.

That's essentially what Elizabeth was thinking about with all these deaths, that these were human beings like her and she was ending their lives. With Erica she had good reason to kill her but didn't want to. Literally she didn't want to since she had no reason to--for her purposes it was better if Erica was alive and her husband was still going to meetings. But she killed her because she was in pain and her husband was asking her. Then Jackson was someone she wasn't sure about but she erred on letting him live. By the time she got to the negotiator she felt strongly that not only should she not kill him, but he needed to be protected.