The person that brings it up and wants to complain....
Take a piece of rope/string and tie his hand up against his shoulder by passing the rope around his wrist and through his armpit...
And then say "Okay, let's see you do what he does. Then you tell me if he's gaining an advantage."
Smile big...
"I think he's okay. However, if you would like to even out the competition, we can leave you tied up during the game."