Because the answer had already been deleted I hit "no action needed". Of course the system did it's rather insulting "stop look and listen (you imbecile)" response, I assume because that would typically allow the answer to stand.
The answer was already deleted, why would I select anything else? This seems like a bug, or at least a situation that the reviewing system doesn't handle well. When I review I don't just look at the answer presented to me, I often open the question and look at it in context.
The systems "be more careful with your reviewing" response comes across as rather insulting, to the point that it puts me off reviewing.