Well, I can't see that a person's age alone is reason to disregard any negative experiences or points of view they might want to express. By that logic you should disregard extremely positive, sycophantic or adulatory opinions elderly people might have too. I do agree, though, that any information provided, particularly about events taking places decades ago, needs ideally to be corroborated by other forms of evidence, be it other interviews, archival sources, or the printed record.
Again, I'm curious. You seem to be conducting your own research. Aren't you intending to publish some of your findings at some point? It seems to me it would be a useful supplement to the existing scholarship on Moorehead's life and career.