Why would they want the state of the universe to be unnatural on Earth but natural outside the solar system?
edit: I think aliens that wanted to prevent us from colonizing the universe would either destroy us, or (if they cared about us) help us, or (if they had a specific weird kind of moral scruples) openly ask/​force us not to colonize, or (if they had a specific weird kind of moral scruples and cared about being undetected or not disturbing the experiment) undetectably guide us away from colonization. Sending a very restricted ambiguous signal seems to require a further unlikely motivation.
Why would they want the state of the universe to be unnatural on Earth but natural outside the solar system?
edit: I think aliens that wanted to prevent us from colonizing the universe would either destroy us, or (if they cared about us) help us, or (if they had a specific weird kind of moral scruples) openly ask/​force us not to colonize, or (if they had a specific weird kind of moral scruples and cared about being undetected or not disturbing the experiment) undetectably guide us away from colonization. Sending a very restricted ambiguous signal seems to require a further unlikely motivation.