That is super interesting. If I understood it correctly, its like using a Wi-Fi channel as a radar system that both your device as well as an attacker are connected to. And then based off of the interference of your hand when typing, it knows what buttons you pressed. I don't think it would be a practical attack vector because the attacker would probably need to know the physical size dimensions of your phone. And also in an age of phablets not everyone can type with one hand, which may throw off the results.