I think you're completely missing the point of the article, which is saying (as I've been trying to explain here as well) that the silence, or inaction, still has a negative effect. It still causes harm. It's completely irrelevant whether you want to classify it as an action or not; it has a result, and the result is negative.

edit: and I fully acknowledge that I let myself get dragged into a side discussion on it, which I shouldn't have.