There is MORE than enough good evidence out there to show that David Rountree should not be invited anywhere for anything. Here is clear documentation of fraud with regards to his claims about himself and his knowledge of physics and archaeology. In addition, he threatens people. Nasty stuff.
We can see that Rountree tells a lot of lies. Why does he do it? Essentially I believe that David desires an air of authority. Like many mediums, psychics, demonologists and the like, he seeks to give himself abilities and powers that set him above others in his field. He claims to have access to knowledge beyond that of his peers. His desire to be considered a source of wisdom is telling. Roundtree wants admiration and respect but doesn’t want to work to earn it. He seeks it the easy way, by lying to obtain it.