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?
Why? What does that achieve?
Kirk shouldn’t be so stupid that he can’t figure out what “dumb” and “ass” mean when you put them together. Especially when both words had already been in use for centuries by the 20th century and English had clearly barely changed in the following centuries.