If he wants a truce he'd better start changing his habits and be a better person:
1. When selling on eBay, be more communicative and friendly, less sceptic towards other people, and Paypal might help too (I would never send cash even if I wanted something from him). And stop asking ridiculous prices. $500 for a bog standard A4000 is completely outrageous.
2. Accept that there are people who like all sorts of Amigas and -derivates. Stop calling non-A2000s pieces of cr*p.
3. Not acting like "I know it all better", but listen to other people's arguments. When in disagreement, use arguments instead of foul words.
I'm not really prejudiced, but I think he has to go through a lot to clear his name over here (and other places).