If there are three or four good moves of approximately equal strength in a position, then it just isn't a position where someone at grandmaster level needs to cheat or benefits from doing so. They were going to find one of those moves anyway.

Is it cheating if you make decisions to purposefully not gain an advantage (ignoring gambling-induced outcomes, like throwing a match)?

"He was cheating! An outside influence was telling him which move to make and he purposefully didn't do it!"