Hear me out.
Last year, Oddfellow's whole thing was wanting us to 'conquer Fear', and how he wishes to become the most powerful being in 'this universe and beyond!'.
And of course, Adaru is the God of Fear, so he would not be happy about this, and for possibly the first time ever, he himself feels Fear. So despite not being able to leave the Lantern for another 7 years, that first feeling alone of Fear is powerful enough for him to project out into the real world, or perhaps create a spawn, all to reinstate/remind us of his power status.