Okay, I’m no expert, but here’s how I see it.
Green Lantern got his powers when the previous protector of the Earth-zone-sector crashed to Earth and gave Hal Jordan (or whoever) the magic ring that chose him as the new protector. Before this, no one had ever heard of the Green Lantern, the planet had no aliens, nothing attacking it, no giant yellow clouds or sinister aliens bucking to destroy some shit.
But gee, after the new GL became human, there’s all kinds of shit attacking the world. Does someone want to investigate this guy’s work-ethic? Maybe evaluate his performance. Whoever these aliens are that watch all the Green Lanterns, maybe they wanna check out how this guy’s doing on the job. Because there sure wasn’t this much trouble before.