Just from the abstract it seems like this could be defeated by spy camera manufacturers by placing a Faraday cage around the camera components. It looks like they acknowledge that under Limitations:

> The latest smartphones employ low-power DDR techniques [49][50] and integrate Faraday cages internally to mitigate electromagnetic radiation (EMR) leakage [51]. The combination of the two measures significantly increase difficulty to detect smart- phone cameras’ memory EMRs using the current ESauron prototype.