To the people saying: "they had to! so many coins too much for one person to own! they can attack the network!"
Just think about it.... those coins are being rolled back and going back to one entity.. Mintpal.
If it is unsafe in one entities hands, what does it matter if that entity is the hacker or Mintpal when it comes to the security of the network.
If the system inherently protects itself, as Bitcoin and all crypto's are allegedly designed to do, then it will protect itself in hands of hackers as well as exchanges. If more is to be gained by holding the stake than abusing the stake then all is safe.

If I was the hacker this is what I would do:
(Hacker take note)
I would send most of the coins to a ridiculous and inaccessible wallet called something like Mintpalsucksandhasnosecurity.
In that way you would destroy the coins, keeping a fee for showing this flaw to the community.
This would also negate the main reason for a rollback.