Are you familiar with Christopher Hitchens? That which can be asserted without evidence, can be dismissed without evidence. Until the author provides evidence of their claims, there's nothing required to dismiss them.
> The assertion that someone made up a story is the logical conclusion to the assertion that there is no evidence to back up their claims.
It is a logical conclusion. One might still arrive at a different logical conclusion.
Maybe you're not familiar with the practice of journalism where anonymous sources are routine, and have successfully uncovered a great deal of misconduct by governments. Reserve skepticism of course, but dismissal of a routine practice with a proven track record is not justified.
However, given all of the information known at the time, there's little evidence to suggest that anyone aside from them was responsible for the assertions without evidence, which again leads to the same logical conclusion.
Right, and these claims are being made by an award winning journalist with a proven track record who has a source. That deserves more credence than just "anyone" making any claim. Not enough to accept it as truth, but far more than claims that can be outright dismissed as you initially claimed.