If what you wrote is true at face value, you are an entirely unsuitable person to hold a pilot's licence.
A couple of things...
Firstly, everyone makes mistakes. Unfortunately this one is likely to cost him serious coinage. A phone call to the manufacturer immediately upon discovery of fuel contamination would be my preferred route, but hindsight is great innit.
Secondly, he doesn't state that he flew it again (which I surmise as being the inferred source of your criticism).