It's quite interesting to see that this bug is present. I had always assumed that all multiplayer transactions would follow the same model as the financial servies industry to prevent such exploits occurring (where I worked before being made redundant).
In this model, a dealer would buy (for example) 50 tons of grain on the commodities market from another dealer (known as the counterparty). The dealer sends notification of his trade to a broker and the counterparty sends details across as well. The broker matches the trade then sounds out a confirmation to say that the trade has gone through. Of course, all this happens electronically via STP (Straight Through Processing) and many 100,000s occur per day. Should there be connectivity issues or server problems, then the trades can be queued up and flushed through when services are back online (and believe me, when services are down, there are a lot of people trying to fix it

).
Extending that model to ED, I could see the Elite servers acting as a trade broker so that any attempt hack the client side would be rejected. Obviously, there would be no counterparty to match against, but the concept of trade confirms could be a useful model.