"what matters is whether something needs more or less energy than the alternative"
Does it? Does Mother Earth care whether your pollution came from a car or bicycle? You're just another polluter, you big bad polluter you.
More seriously, I think the reference here is to the idea that you can somehow objectively measure your negative impact and that anything above zero is bad. Since I pretty comprehensively disagree with that statement (impact to something as dynamic as the ecosystem can not be measure concretely, most people's metric of "impact" are incoherent when you really examine them, zero impact isn't a useful metric in light of these things, and I have at least as much "right" to exist and impact an environment as a beaver), I tend to agree with you. My point here is that it depends on your point of view and there are common points of view that disagree with you, and the piece was very clearly invoking this "radical" green point of view very often.