He agreed to a deal with a seller and once escrow was setup he backed out of the deal. This is a sign that he was trying to avoid using escrow and only agreed to accept escrow to avoid setting off any red flags to others. Despite this being a bad idea, often times people will simply agree to trade without escrow if one does not respond and setup escrow quickly enough.
A neutral rating is more appropriate then, since no coins were lost and no scam was attempted. People are allowed to back out of deals. You should put in the rating your belief it's a sign he was trying to avoid escrow.
The scam that was attempted was that he tried to scam the bitcointalk account from the seller. The reason given in this thread was something along the lines that he did not trust me, however that is contradictory to the fact that he asked me to escrow for him.
To perhaps come at this from another direction (tl;dr 14 pages over again), did worhiper_-_ ask you to escrow 1) before... or 2) after...
...reading a ToS from you to the effect of "Quickseller escrow terms are at the exclusive determination of Quickseller. Buyers and sellers do not get to set any escrow terms themselves. By hiring Quickseller as your escrow, you agree that you are bound by these terms."
If worhiper_-_ did knowingly violate that clear and effective ToS, then neg trust is warranted for depriving you of your escrow fee (time=money). If worhiper_-_ did not knowingly violate that clear and effective ToS, imagining that escrows are merely there to do whatever the buyer and seller agree the escrow should do, then neutral is.
If I were you, I would require escrow counterparties to clearsign their agreement to that ToS before PMing you anything else at all.