If you'd like a good case for precedent, check out the case with myself and Traxar.
http://www.sythe.org/report-scammer/1634712-r2pleasent-post12811087.html
Traxar wanted me to sell his Blue Party Hat. I told him I didn't want to take a big risk. We agreed to let me on his account to do the trade. Between me selling the Party Hat and walking to Lumby bank in order to sell the gold, the account was banned.
Sythe staff found me to be FULLY RESPONSIBLE for the Blue Party Hat, even though it never left the seller's account, and I never agreed to take responsibility before-hand.