I see what happened. I had Altaria selected in order to speak to them, so the cheat code made their worlds mine. I started a new game, didn't select any planets and surrendered to them, hit CTRL Z and pressed turn, now Earth says it belongs to the Altarian Republic and all the AIs are moving around scouting and colonizing. I can't manage the Altarian worlds this time.
You do know that you don't actually HAVE to surrender to anyone in order to make this work? Destroy all of your ships and colonies, and then you will be gone w/o having to worry about surrendering. This helps when checking a game for balance, as you don't "contaminate" the experiment by giving your assets to some other race.