Greer, like most other ufologists, is a fraud and a charlatan. And like the rest in his field, he's built a comfortable business on bilking money from the ignorant and those that will believe anything, simply because they lack any faculties to think critically on their own. I wouldn't trust him to give me medical treatment, but it's also not difficult to understand why he'd give up his practice given that he charges about a grand to teach one to (and this is a direct quote from some of his lecture materials) "initiate contact with ETs using consciousness, coherent thought, lasers, electromagnetic signals, and group processes." Oh, yes, there's an enlightened soul for you.
One would have hope that twenty years of the so-called Disclosure Project and Greer himself would've yielded some kind of tangible fruit, even if only some kind of workable, testable theory. Instead, his assertions follow the same twisted branching of logic as most in his predatory occupation: aliens exist => UFOs are aliens => UFOs possess advance technology => governments have capture UFOs => governments have advanced technology.
Of course, that all flies apart the second that you take little gray/green/reptilian/Reticulan men out of the picture. The real problem with him and those like him is that they give no thought whatsoever to the fundamental problems in asserting that the governments of the world, or the NWO overlords that are alleged to hold their leashes, would be at all capable of reverse-engineering alien technology.
First, there's the anthropomorphic dilemma. Aliens, the occasional anatomical grotesquery notwithstanding, are usually conceived as more or less resembling a human: bilateral symmetry; bipedal; two limbs dedicated to locomotion, two for manipulation; clustering of sensory organs. The problem, of course, is that such conceptions patently absurd, as is the notion that their physiology would permit safe travel to and upon the Earth; this would require that they developed on a world of a specific temperature range, specific gravitation intensity, and an atmospheric similarity of laughable probability. And that's totally ignoring the degree of unlikelihood that the placement and function of their sensory organs being virtually identical to ours.
But let's assume that all of this happen, there really are Martians, and they visited this planet, for reasons about which I wouldn't even hazard a guess. Human leaders, shadowy and power-hungry (we've all watched a few late night episodes of The X-Files, amiright?), manage to nab one. We find ourselves smack in the middle of the congruity dilemma. The probability that we would be able to comprehend, let alone reproduce, technology hundreds, thousand, or tens of thousands of years ahead of our own is virtually nil. Don't believe me? Imagine you have a time machine (since we're already dabbling in absurdity) and an iPhone, a virtually ubiquitous device today. You go back to three different periods, separated by orders of magnitude, 20 years, 200 years, 2000 years, and present the . At twenty years ago, you would be hailed as a technological genius and probably create a business empire in the bargain. At two hundred years, you'd be hailed as a prophet, and hold sway over thousands. At two thousand years, you'd be a god. That is until your battery ran out. That's the problem. We could no more understand or duplicate a gravity drive or inertial dampener than a habiline, possessing a stone club, could understand or utilize a nuclear warhead.