'Controversial' study about possible ETI contact scenarios

[zenmaster]

Interestingly enough, there is talk of the "zoo hypothesis" that our planet is off-limits by ETI, and that they are waiting for a particular benchmark to come visit us.

How are these ideas different from 'The Day the Earth Stood Still', or the non-intervention 'Prime Directive'. Don't these questions naturally arise when people start considering cultural relativism and the disruptive impact one culture can have on another? Lot of ways to interpret lack of 'yellow-ray' interaction.