I've never seen it necessarily that she gave up the kill possibility outright or just for the Birds, but like she said, Dinah was helping her learn mercy, and the clarity of mind (that's a bad way to phrase it, but i can't think of an alternative right now) to consider other options when applicable. Back her into a corner and it could be fatal still, especially if her team's in jeopardy, but it's not something she'd default to.