I just love that response. Reading this, the excuse of "friend's home" just doesn't jive with what is described as a progressive inspection (some at low level) of multiple homes. There are some parts of the description of events that read like peeping tom.
If you own a drone and think you can just fly over someone's personal property to do whatever, then you should also be responsible for the risk involved you'll lose your expensive toy.
When you are outside, the right to privacy gets very hazy. Are you going to stand in your yard and say “No one can look at me”? The question is whether they were stalking.