Actually - allowing limited withdrawals makes sense - they must fear a 'run' on BTC either crashing the exchange (with it's new software fix being untested, too) - or meaning they have so little liquidity that their business is finished.
From what I have read, Mark is holding at least 40,000 BTC that do not belong to him, whose owners have been trying to withdraw for months.
Does that make any sense?
no, those bitcoins in failed tx were stolen with the bug of send new mined coins, tx fail and modified mutant transaction with diff tx id gets relayed by hacker and then gox credited back the btc. rinse, repeat.
the failed tx you saw at coinsight.com/mtgox are because gox accounting program still thinks those coins are unspend.
but they are gone.
and it's gone. Gone!