That's an interesting idea: trying to create so many false positives that the user gives up. We're already removing around 100+ false positives per frame at the moment in difficult cases, so perhaps it's possible to overwhelm the filters with very maliciously designed environments.
I think the easier way would be to hide the cameras in much harder-to-reach places so that it's inconvenient for the user to get their smartphone near. This might reduce the kind of videos that can be taken, but maybe an attacker will find that a reasonable tradeoff.
Probably the very smart spy camera can detect off axis TOF artificial light and close a shutter over the lens. Assuming your app integrates over the scanning motion, the camera won't be detected while it's shutter is closed. After the illumination is completed the spy camera can re-open it's shutter.
The spy camera could also something like your system to detect the phone camera and take defensive measures.
I think the easier way would be to hide the cameras in much harder-to-reach places so that it's inconvenient for the user to get their smartphone near. This might reduce the kind of videos that can be taken, but maybe an attacker will find that a reasonable tradeoff.