Mt. Gox was not a ponzi scheme. It was a legitimate exchange business that became insolvent, and it was the users (not just investors) who got screwed.
Also, the term ponzi scheme get's used a lot in discussion about bitcoin, but many people do not know that it is a very specific type of scam. There have even been actual ponzi schemes involving bitcoins (not Mt. Gox). The people scammed in those were not insured because it was an investment, just as the people involved in the Maddoff scam were not insured. That is why it's disingenuous.
It was not a ponzi, but MtGox became insolvent through fraud: Mark Karpeles simulated fake transactions with fake coins and fake dollars using his willy bot.
Also, the term ponzi scheme get's used a lot in discussion about bitcoin, but many people do not know that it is a very specific type of scam. There have even been actual ponzi schemes involving bitcoins (not Mt. Gox). The people scammed in those were not insured because it was an investment, just as the people involved in the Maddoff scam were not insured. That is why it's disingenuous.