[Houshalter]

Why would they want to hide? You are making a very strong claim about the motivations of aliens.

[tyingq]

SciFi usually offers this sort of explaination: https://en.wikipedia.org/wiki/Prime_Directive

[Houshalter]

That's a very forced explanation by science fiction writers to justify it. I wouldn't expect actual alien civilizations to invent such an arbitrary rule.