You can not prove this in anyway possible.
The Ki does not make a practioner a superman it provides another option of dealing with a punch and kick. Yes we can be rocked in a fight as well. But, it is alot harder to do so. A simple demostration can clear this whole matter up about the Ki. Trust me you are making this into something much larger then it is about this Ki. If it is bullshido then lets do a demostration. A gentleman agreement with sign contracts for liability. And you get the guys to deliver the strikes and kicks. Why put down something that you are not willing to explore up close and personal. It can be done friendly and no ego.