Here is the rundown of what is going on at MtGox.
1) MtGox lost dwolla account to seizure. This is still their money, but have to get it back when/if the government allows them.
2) This strained MtGox, because now everyone requested money via wire, and funds were limited. Coins were bid up at MtGox out of fear.
3) This is leading to even more stress at MtGox, due to the fact that it is more economical to deposit at other exchanges. Example, if you were to wire $10k into an exchange, would you wire to an exchange where you can buy BTC at $94 or buy at $99? No fiat comes in, no fiat goes out.
There have been no credible reports of BTC not being withdrawn, and there must have been many thousands of coins taken out of the exchange. I've personally asked for a large cancel of funds, which MtGox did so within hours. I bought the coins and withdrew them.
This leads to my conclusion:
Gox does have the funds and the BTC to back everything up 100%. But they need to clear government regulations for it to happen. They can't come out and say "Stupid USG won't give us your money", it would lead to a panic run on the exchange as coins get bid up. It also would not help clear regulations with the government. Therefore, it is in the exchange's best interest to stall.