Helicopters cant see anything but surface temperature, they cant scan your house.
If someone has a big heat sig from a window or has a grow in a loft they can see the higher surface temp(sometimes).
Just because they see a hot window doesn't mean someone is growing anyway.
I think they need a warrant in the US just to point a FLIR camera at your property , might be wrong.
Get a light proof curtain or some panda film / mylar to stop the light. Garbage bags isn't going to do much.