No , "Ponzi" the word itself is not worth of Trust , its main essence is to pay to early investor with the money of late investor and as soon as the total deposit exceed the owner wish(planned) , switch off the site and good bye !!
Did you read?
I told that this would be a system where the owner cannot take all of the invested money. The owner simply wouldn't have every private key (and as you know, you cannot spend bitcoins without the private key).
How the operator pay to investors or use the fund for their project ( if any ) when they have no private keys on their wallet ?, I would like to know more the system of this ponzi. FYI , I don't trust ponzi at all before.