Which, I believe, is completely irrelevant to the problem described in the article. What they do is observe the electromagnetic spectrum, using WiFi routers as

Which, I believe, is completely irrelevant to the problem described in the article. What they do is observe the electromagnetic spectrum, using WiFi routers as signal sources. They don't really care what sort of data routers are transmitting, they need the transmitter active at the moment you press the key. (It may even make it somewhat worse, as the router's transmitter is less likely to idle. Although I'm not sure if it matters.)