Yeah, the existence of dark energy. But I haven't seen even the barest attempt to make any sort of argument about why dark energy would cause UA. It's merely a scientific-sounding word masquerading as an explanation -- from the looks of it, someone sitting at their computer said, "hmm what plausible explanation might there be for UA? Dark matter? Well, they're both things we don't understand, so I can probably get away with saying this." That's a hypothesis at best, not a coherent theory.
Meanwhile, gravity is a well-tested theory, a fact that I've stated and that I've invited you to critique. You do an awfully bad job at responding to direct questions though, Junker, especially for a site administrator.