The keyword being "once". He has been found cheating several times now and that's where my clemency reaches its limits. I'm all for giving people second chances in most cases, but if you don't learn from such mistakes and try the same stupid thing again and again, then this shit you've caused for yourself will indeed stick forever, and rightfully so.
I aimed to cover both sides of the medal with my post, inlcuding that quote...and besides that, I know about a lot of shit I did when I was way younger - so I tend to be forgiving when I get the impression that person wants to come to terms with whatever deficies have been shown. There also is a thin layer between righteousness and self-righteousness. But we're already in the middle of "talking about somebody" which I actually won't continue without the subject(s) of discussion actively involved..