I think he should give our money that we donated to the WS event to the foundation. And the foundation should assure to organize the WS event.
He should use the whole USD amount he obtained. Even if these are double the coins.
I as a donator would be fine with that.
The correct and only sensible course of action is for IE to refund every person who donated money to him. If they want the money back of course.
Explain to me how can I verify if someone sent a donation if it is sent from an exchange? I would ask the person to send a small transaction to verify it is his/her account. I can't do that with an exchange. Nor will I be able to send the funds back to an exchange from the outgoing address.