From a legal perspective for mtgox you really couldn't hope for better news, not only have their systems been tampered with but now there is undoubted proof.
Just paint yourself as the good guy amongst a scene of money launderers, hackers and drug dealers. This isn't proof of fraud, it's proof that people broke into their systems and tampered with them.
The attackers here broke in and stole a DB copy, they may not have been able to tamper (e.g.: they had access to a backup of the DB but not the running copy)
It's probably still a good part of a "we're incompetent not malicious!" defense, if that is how they decide to handle things.
Just paint yourself as the good guy amongst a scene of money launderers, hackers and drug dealers. This isn't proof of fraud, it's proof that people broke into their systems and tampered with them.