I'm actually pissed. I f*cking HATE this decision.
I really hope that there is more to the story. Maybe later we get a longer message, or we learn that the message is "real" but was altered by Brainiac or something.
On this subject, Gunn seems to be inspired by John Byrne's depiction of Kryptonians/Kryptonian society, which I hate.
James Gunn claims that his Superman movie is an "immigrant story". So then the message of the movie is that immigrants are dangerous and should completely abandon their heritage? Wow, that's f*cked up.