I realize you can just answer, "mysterious aliens beyond our understanding," but why would a space probe have a mandate of either talk to a whale for 30 seconds or destroy Earth and disable everything in its path on the way to Earth?
Just finished watching DS9 Season 6 Episode 10 'The Magnificent Ferengi' ..... and totally fun watch complete with the worst Ferengi in the series and a great cameo by Iggy.