It depends if we're judging the overall predictions of everyone, or this specific author's predictions. I always tend to look at it at the author-level, because otherwise the infinite monkeys theorem applies anyway.
I think this author should be given credit for the accuracy. He can't control what everyone else is writing and how accurate or inaccurate they were. He can only control his own predictions, and they were very good.
I don’t think we can look at this at the author level. Imagine if we had 1 million different authors making predictions, certainly some of them in the population will be very accurate and in retrospect they’ll look like geniuses.
I think this author should be given credit for the accuracy. He can't control what everyone else is writing and how accurate or inaccurate they were. He can only control his own predictions, and they were very good.