I think you cannot sue mtgox, I mean you can sue but you will lose.

The problem is that you didn't verify your account. This means that they can never know if you are the real owner of the bitcoin.
You could just have moved the coins yourself and then try to double them by blaming mtgox. Since your google account got hacked, how could mtgox know anything?

If you had a key to your safe, but the bank does not know your identity. Then how can they be blamed for the usage of that key? Obviously they cannot know who is the real owner and who is the hacker? How can they know that it is the owner that requests the funds to be frozen? Mtgox will claim that the funds have been stolen in November.

I am very sorry your coins have been stolen. However, I wouldn't advice trying to sue and spend even more money. Since you are in China and you would need to sue a Japanese company it will even complicate more.

You could try to keep talking to Mtgox and they might try to refund if they are nice.