This applies to a different legal and monetary system than what has applied to Bitcoin so far. In another jurisdiction, the onus may be placed on the client to perform due diligence.
I don't think it makes any difference what thing of value was exchanged, whether currency or commodity. If you think it makes a difference, please explain why.
As for the onus being on the client to perform due diligence, that does not mean what you think it means. If I hire a contractor to do work on my house, it's my responsibility to do due diligence to make sure I hire a reliable contractor. But if he sets my house on fire, he can't respond, "It was your responsibility to make sure I was a good contractor". That's just silly. That a victim's stupidity made him easy to victimize is only relevant if the question is how much we should feel sorry for the victim and how much we should hate the perpetrator. It doesn't change the victim's right to restitution or the wrongness of the exploitation of the victim. (It's just as bad to rob an idiot as a genius.)
And how would profits be forcibly returned? What if off-blockchain transactions were conducted that broke the chain of ownership? We'd end up discussing taint again.
If you kill my cow, you are not expected to resurrect the cow to return to me. You are expected to pay me the value of the cow. The same thing will happen here. If people who were the beneficiaries of fraudulent transfers can be identified, they can be subject to claw backs.
Also, something good coming from a Ponzi?
Quite the reverse, charities have historically been major victims of Ponzi schemes, just as they were here. The charity here was subject to a claw back.