I mean that the author was literally writing a book about this and literally conducting an investigation about who was the real author of the TIFF spec. He interviewed other people about it, he had a name that had a typo in it, he even found a white-on-white line in a PDF with the real name. He was clearly putting effort into the research.

We are humans, everybody can miss things, I mentioned "hindsight is 20/20" but still, it was in the Wikipedia discussion page for the TIFF article all the time. It's a matter of fact and some random HNer found it in minutes/hours.

I repeat myself, it was probably better that he didn't found that out and went to write a hand-written letter to the alleged author's home address, it created a much deeper human bond, which is especially meaningful since Stephen Carlsen passed away not much later.