I am not a lawyer (but a parent and uni. teacher), and very easily have reached the same conclusion as this article. First, their motivations, as the article emphasizes, leads one to the truth. Second, the simple fact that when she was asked about an FBI investigation, quite naturally she said yes, while he was obviously consistently very nervous when asked that question and in addition to not agreeing to one, gave silly arguments against one, including polygraph - while you would have expected the opposite. Especially as a lawyer, you would have expected him not to ask, but to demand a formal investigation. Thirdly, their demeanor/performance did matter. She was a person who had never been in a courtroom and her authenticity could not be mistaken. While he, is a creature of a courtroom, and came across extremely unauthentic. I believe anyone with basic critical thinking functions could see through all this.
As far as reasonable doubt goes - this is not (yet) a criminal trial. The issue is simple, there are a ton of other people who are similarly qualified as him. And, in fact, he also has come across as quite average and incompetent for the role of a “supreme.”