At a minimum, passive radar could be useful to augment more conventional types of cameras in a home security system, especially for someone with acres of land with a lot of trees, etc.

I'm pretty sure he asked because it's not uncommon to see mmwave radar on flagship smartphones, especially on devices that don't have lidar. Many cars also have radar for parking assist or automatic parking.

No one knew how personally useful radio transmission could be when it was in the exclusive domain of inventors and governments. Radar is not very personally useful yet. It has lots of non-military and non-professional applications that will open up as it becomes cheaper and more accessible.

Restricting code like this will make zero difference to governments or any motivated, well funded, capable group. It just hampers the rest of us.