The advertisement itself was inside the code of the attachment to my understanding, not on the thread itself. Therefore any "evidence" other people might have posted (next to useless since only staff can see edits done to a post and the unapproved attachments) would have simply been a waste of space, and not usable towards the dispute. Unless of course they had outside access to this particularly attachment.
I would also like to point out this, this, and this is not exactly evidence. He also deleted a post which directly pointed to the ad inside the attachment. So it can hardly be called bias. In any case, disputes are meant to be between the disputer and the staff. People chiming in with guesses and opinions are not allowed nor helpful. Your ban will be lifted, but please refrain from commenting in staff disputes not of your own.
Solved and Closed.