As corey said, I didn't ban him. And you are addressing me as though an appeal to my sensitivities would change the facts of the case. Receiving stolen property in full knowledge has always been a bannable offence on sythe.org. Publically posting a guide on how to do it is also a bannable offence.
You seem to be labouring under the delusion that everything on sythe.org is immoral by default and therefore there is no difference between legitimately obtained virtual goods and stolen virtual goods. I am here to tell you that there is most certainly a difference, and further there is nothing immoral about trading services with one another. It's a basic expression of your freedom to contract with whomever you choose.
And re: jagex's terms of service / contract with you. If you buy and sell services with other players you may be breaking your contract with Jagex... if Jagex's ToS can be regarded as a contract in the first place. That's your choice, your issue to deal with. I would point out that you never signed anything, and that trading services with other members does not lead to any damages to/against Jagex. In other words even if they had legal injury as a result of you trading freely with a third party (very unlikely) then they would still lack any damages. Legally then, it's not an issue (legal injury: maybe, damages: none). Morally it is certainly not an issue (it is not a violation of the non-aggression axiom.)
Further, when you sign up to Runescape, Jagex gives you the right / access to exchange their virtual gold. They put restrictions on this right (according to their contract; which is questionably valid) which involves your intent. That is: if you intend to make a real profit from trading their virtual tokens then they say you cannot do it.
However legally you are allowed to give gold away for free. And legally people are allowed give you real property for free. All gold trades are broken naturally into two pieces anyway, as you cannot have a direct exchange of gold for dollars. That is: It's always a blank trade (i.e. exchange for nothing) in Runescape, followed by a blank trade in real life.
You certainly can have a contract to exchange gifts with another person. So I would hesitate to say you were even breaking your contract with Jagex, if a contract can be said to exist at all.
Hope that clears it up for you.