I respectfully disagree with the quote above, a BTC exchange MUST have both the option to buy BTC with fiat AND to sell BTC for fiat. If on one side there is an in-balance/delay, then it is not a proper exchange, and in the "real" financial world this would mean they would be out of business in not more than 3 days. And this is what I believe is going to happen with Mt.Gox (but I don't mean in 3 days). But I really hope I am wrong and this is not going to happen, but I am already OUT of Mt. Gox, impossible to do serious work with Mt.Gox as a partner.
But I do agree with the other part of the post of the same author, about cancelling Mt.Gox fiat withdrawals, buying BTC, holding them in an offline wallet or transferring them to another exchange for fiat withdrawal.
Yes, I considered editing that line out knowing someone would call me on it reasoning exactly as you did.
I left it in because Mt.Gox does still allow the exchange of BTC for fiat. That's not the part of the process that broke. Moving that fiat via certain channels is where the problem arose.