Well it is the escrow's job to ensure the trade goes smoothly, and if it doesn't to see that the scammer does not end up with the money. That is what they are getting paid to do. If the escrow is not willing to do basic due diligence before releasing the money, I don't see the point of using them.
The amount in question in this case is $50k. I don't think it is unreasonable to use a little bit of care when dealing with that much of other people's money.
How would you care more when the same person (here same account) is telling you to make a change in the deal? If there was no hack involved we would not see the scam. The situation was real tricky and anyone would have been victim of it. MJ did not keep the money after all.