I'd probably use closer to 10W as the device power level (a standard laptop, what I'm using right now), so the number for me would get close to 0.2g, but your point stands; the article is answering a different question than I was assuming, but regardless it seems that the majority of the energy is clearly the local device.
Definitely the peak would be higher. My laptop has a ~60Wh battery and gets ~6hours of battery life, so I was just assuming 10W average for web browsing.