In my opinion:

• This is misleading because you charge for a service you're not providing. (I think we can all agree on that)
• Apart from the fee, the escrow isn't used because of being a third party, but because of having a trusted reputation. If the deal would be with the escrow directly, the other party likely wouldn't require an escrow. (I'm not sure if we can all agree on this one)
• There isn't any more risk than any other deal in which the escrow deals with 2 real parties instead of his own alt and someone else. (I think violating this deal would be the same risk and result in the same reputation damage as violating a deal with 2 other parties)

And this is mostly speculation but I wasn't arround at the time: did QS escrow this deal because he didn't want his alt to become known? AKA the main reason to do this was to secure his account farming at the time? Or did he knowingly suggest himself as an escrow to mislead the other party in pretending they are different people?