you're essentially regulating the currency. Bitcoins are not meant to be regulated. If you want regulated currency where a central agency says what's right and what isn't go back to using your worthless paper money.
That is all.
Its not regulating. Its a private business deciding what to do. He just has to fulfill the contract with his costumers.
On the other hand, the costumers are free to change business and take their business elsewhere. Honestly, after this, anyone using MtGox deserve what he/she gets.