Cero appeared above the atmosphere of the planet, waiting for someone to notice him. He learned from his subjects that a exploratory ship had come near his planet a while back, and only now decided to bother responding(well, they WERE gracious enough to heed his desire for them to get the hell away from his planet while he wasn't there, and besides, he was bored). Sure, it might be seen as rude to only now respond, after a few months(maybe a year? He hadn't bothered counting, really), sure it may seem crass. But honestly? He was a tyrant who killed most of the population of his planet out of boredom before naming himself king and enslaving the rest, keeping only a few people as citizens to take care of the place while he was gone and keep the slaves in line. When it came down to it, what did he care what these people thought?