The confession referred to in this and previous interviews with Ben was only made to him just before the Athens Olympics in 2004. I think it was actually quite a while (some years?) later before Ben managed to get the guy to make the same admissions in a recorded conversation.
The lawyers would have had a stroke over some of the stuff - Ben’s grammar for starters 
- and pulling together the money and expertise to self-publish all will have taken a lot of time.