That's pretty cut and dry though. Any player deal that someone doesn't follow through on, GMs can check the logs and find the seller didn't deliver what they promised. The problem in my scenario is you end up with 3 parties who have done nothing wrong, and then what do you do? Give the buyer the house? Then 3rd guy loses. Force a refund? Seller loses. So allowing it becomes a problem because if SE says "sure go do it" sellers can potentially be out too, and who's to say the buyer doesn't line someone up to run in and snag it, buyer pretends not to know the guy, makes a complaint.
But you haven't talked to every GM and the point is there's been GMs on record saying it's OK.