it is worse even: the buyer can scam everyone, the trade mod can scam anonymously, the seller alone can not really scam.
there is no way any outsider could prove, disprove or verify that a name "lost" is with either party. the buyer can just have an alt, take the name there, say d'oh it's taken, doesn't have it on his main. neither the trade mod nor the seller could ever find out if or if not the buyer got it. so the trusted middleman does not help at all, bc all that brings into play is another party that could anonymously steal the thing of value. a 1:1 would be fairer in that the risk were evenly distributed between buyer and seller: both could do at some point during trade make the bitch move of snatching it on an alt and leaving with arms and the name. the situation would be that whoever went first would have the risk. arms first: buyer at risk, name first: seller at risk. it is even. with a trade mod the trusted reputation won't help. he could snatch it himself and still keep his reputation. the buyer could snatch it and the trade mod couldn't verify and would have to hand arms back leaving the seller without the name, the buyer with the name and the scam done in an untrackable way.
but... there is hope: you COULD buy an extra account, put the name on there, use a trade mod to transfer the account, let the buyer link it to their email (in order for the seller bot able to grab back by password reset or other) and the buyer could then at an undisclosed time to anyone else transfer the name to the main acc. that however would violate eula, would be trackable by anet - likely be persued and possibly end in ban of both accs.
so... really consider IF you want to do a name trade and IF you want to include a third party.