Last year, Willis told the Herald the race in Beijing was still a career highlight, despite the controversy.
"That [Beijing race] is still the highlight of my sporting career. I couldn't have been any more joyful than I was that day. That was an amazing experience, and that's what brought us [he and his family] to peace many years ago in this sport.
"Potentially people left and right of you could be doping, but that's irrelevant because you're trying to get the most out of yourself. Otherwise it makes you angry or bitter and you can't perform to your best.
"I want to be able to run freely with joy in my future races and have fond memories rather than a sour taste in my mouth. There have been times in my career when I've had a cynical approach, but I've been free of that since about 2015."
The 29-year-old Kenyan, a triple world champion, has reportedly claimed his sample may have been tampered with, but anti-doping bosses said the case was "convincingly made out".
The Athletics Integrity Unit decreed his results and winnings between November 2017 and February 2018 should be scrapped. He was initially suspended last year.
The AIU said the Kenyan presented an "a la carte menu of reasons why the charges should be dismissed".
Kiprop has said: "I have been left to fight this on my own. I have had no support even from my fellow athletes, some who have questioned my integrity in public."
A massive 138 Kenyan athletes have tested positive in anti-doping campaigns since 2004.
Kenya has been on the list of countries under IAAF surveillance since 2016.
