While she did try to avoid killing and preferred to get away and survive where she could, she never actually refused or refrained from killing, except with people for whom she cares (Peeta, Rue). I think the reviewer touched on that, that she was never in a position to refuse that option. For instance, the guy from Rue's district letting her go, or the Foxface girl, could both have been instances of morally conflicting choices. Neither was a "villain" per se, and were presented somewhat sympathetically, but they were also conveniently removed without Katniss having to make a choice about their lives or hers, as the Games bosses would almost certainly not have allowed the loophole they made for her and Peeta. She does use the tracker-jackers on the group below her tree, with full awareness of the possible lethality, so it isn't even like she was trying not to kill anyone, either.

She only refused to kill her friend. I think the reviewer was aware of this issue, but complained that she was spared the necessity of having to make this choice when it could result in her death.

Agreed