Looks like someone is commenting on something they don't understand! Mt Gox doesn't do bitcoin trades (as in make tx in the main chain), they do trades inside

Looks like someone is commenting on something they don't understand! Mt Gox doesn't do bitcoin trades (as in make tx in the main chain), they do trades inside of their own system and it's converted to btc when the user withdraws money. You cannot undo a btc tx (one in the block chain). Once confirmed, it's there.