re: We won the Footfall war
Maybe they defeated humans in a space war long ago and sent our species back into the stone age with an asteroid collision.
So now they just monitor our technological progress and debate whether or not they should do it again.
Can you think of a better reason hypothetical aliens buzz our planet yet seem uninterested in making formal contact?
Nobody is going to force they to give up technology so if they had some sort of non interferance directive that logic wouldn't seem to apply.