Baku had been waiting for this opportunity for some time now. He'd been teaching the lieutenant's future self how to perfect his illusions, and he'd been gradually winning over the lady of labyrinths, but to catch them both at once? That was an opportunity he couldn't resist. He didn't tell them what he was planning--no. He wove his web of un-reality around them after they had dozed off, and waited for them to 'awake' in his world.
He was excited--perhaps even capriciously so--to see how long it would take them to realize that they were in still a dream.