I know this because I'm not dumb, and neither is Sponge. He knows what he wants and he's going to do what it takes to get it--vengeance/justice (depending on your perspective) against the parties that brought him down. This includes the majority of the current world, but he's not dumb enough to think he can take them all on at once from his current position. One at a time, and right now the most advantageous position for him to be in is with Vox, chipping away at the vulnerable One Vision position. He's exactly as he has always been.
That said, I'm fairly confident he wakes up and pisses excellence in the morning.