Let me preface this with, I don't think it is likely, just playing devil's^W ETIs advocate. It makes sense to me if the ETIs have a prime-directive-like reason

Let me preface this with, I don't think it is likely, just playing devil's^W ETIs advocate. It makes sense to me if the ETIs have a prime-directive-like reason not to engage but have reason to monitor or study humans. Then the behavior seems similar to teen-agers bashing mailboxes from cars or when the Air Force of one country gets a little too close to planes from another country. Your basic low-level alien tweaking the superiors/humans and seeing what it can get away with.