This concept explores an alien scout that deems Earth "ripe for picking," only for the main force to return to find humanity has rapidly advanced to the space age.

Based on the search results, "Alien Scout" appears to be a popular writing prompt theme (Reddit r/WritingPrompts) or a fictional trope rather than a specific, well-known essay file. Here are the most relevant interpretations:

A concept exploring a stranded alien trying to blend in with "hairless apes" (humans) while remaining a secret, playing on the paranoia of the unknown.

Is this a you read (maybe in the "WP" link above)? Is it a PDF or creative work from a specific forum?