I couldn't quite figure it out... the preprint
helps a little bit, but not much.
It seems to say that a required high-energy correction to Einsteinian gravity will introduce an extra degree of freedom, and it's the energy, or oscillations, in that extra degree of freedom that would behave like dark matter. It has to be unstable, or its effective mass would be too much.
That's just my take on it, though. He's not as pea-soup thick in his writing there as Penrose would be, but near enough :)
This, like many other things, is a way to explain the extra mass. MOND is different in that it deals entirely with the dynamics
; that is to say that the laws have a modified form, not that there is actually any extra mass.
Maybe that helps, maybe it doesn't :)