They can't delete stolen gold, which is the case here.
Steal gold > buy stuff > sell stuff in RMAH > make cash. D3 money laundering.
They can follow the transactions, all trades are also logged, they can just check compromised accounts trade logs and ban the gold receiving side
This is yet another episode in a long line of fails. I knew I was right when I told all those SW:ToR players that that launch was far from a catastrophe. This is well on its way of becoming one of the glitchiest, faultiest launches. And all because of the greed to introduce an (RM)AH. Serves them right.
Imagine that the gold stolen has already changed hands a gazillion times. I really see no way how they can track all the stolen and traded gold sine at some points in this laundering scheme innocent users are involved.
E.g. A steals gold and items from B
A sells items to C (legitimate player - le) on the AH
A uses stolen gold to buy items from D (le) on the AH
A uses the money from items sold to C (le) to buy more stuff
A sells the stuff he bought with C's money to buy more stuff
A sells the stuff he bought from D for money
A has effectively laundered all stolen gold into legitimate items/gold
Now replace A with XYZ since obviously a hacker will not use the account he used for hacking to trade
Either way, the gold and items are long gone, not to mention that most hackers got out scott free from the alleged attack two days ago since every account that got its items back was restores to a Savepoint, it was not a case of returning the stolen items from the hacker and the hacker being banned. Hopefully I'm wrong but if this whole debacle is true and hackers did hit Blizzard and they just cleaned out the AH, I fear the economy is forever compromised.
Hopefully it's just another hiccough.
edit: aaaaand the AH is down again