I don't think its project tsuki no mi.
if it was, then he should be helping Obito instead of trying to use some "trump card" on him. It wouldn't really matter who uses it as long as the world falls asleep in the genjutsu.
I think Madara lied to Obito while he was brainwashing him. Creation of the false world and promise to create peace was simply a ploy to manipulate Obito to do what he wanted.
Obito genuinely wanted peace to bring Rin back even in a dream. But Madara has shown no proof of intending to create peace. He most likely wants the world and senju to suffer his wrath. He simply wants to take revenge against the whole world. Maybe he wants to be the jyuubi's jinchuricki to unleash a different jutsu one thats far more diabolical than the dream world.