I simply dont buy the "delay" in fiat withdrawal at all... never did. I think its simply so they can attract noobs who want to sell btc at higher imaginary price.
I also believe Marks friends and associates have no problem doing arbitrage trading while moving fiat in and out of the exchange without any delays.
This BTC withdrawal issue is an easy way for Marks to reverse the market and continue the same inside trading.
Yes we have issues with tx mutability but most of the invalid tx from Gox is due to their incompetent system made DER tx which is nonstandard to most nodes. Hence open an easy way for the attacker