Based on the information given at this point, I don't understand the ban.
Since the offense is "Gold Trafficking", it can be assumed that Dusith is not suggested to have sold or bought gold, but "legitimizing" illegally acquired gold through either sale or purchase of in-game items (by deduction of the classic definition of trafficking).
The only way this could warrant a ban, according to your own terms of use, would be:
Possession of any item(s) obtained with illegal methods;
OR, if you define things loosely:
Exchanging accounts, gold, items, or any ingame services for another game's features;
Assuming that Dusith pays prices for his items that are - according to the economy on the server - "normal", "reasonable" or "plausible" as an investment for future market developments (difficult to judge, yes, but not impossible by any means, knowing economy developments from retail servers and/or other private servers), the method in which the item was obtained cannot qualify as illegal. Even if he was to pay above market prices for bulks of some items that become more expensive in the future when different patches hit, that is completely legitimate, since it's not like he uses "insider information" as common economy would suggest, but well known developments, since the patches to come are easily accessible for research on sources like wow-wiki or the vanilla database. Edit: Also, assuming he doesn't know or has been told by the seller of a specific illegitimately acquired item, he has no way of knowing if he is buying "dirty" things.
At this point, anything you could base a ban for an exchange of items or gold to another game's economy on - even with chat logs, trade logs, auction house logs and all other data gathered - is pure speculation. That is of course, if none of the gathered data provides solid evidence.
Given that, +1 unban this dude
Regards, Rinku
P.S.: Though I cannot provide evidence for this: I know in fact, that Dusith has been offered money for gold, and declined it.