It seems like the author beat around the bush a little bit, perhaps for fear of making too direct of an accusation. Can someone share what mechanics the player

It seems like the author beat around the bush a little bit, perhaps for fear of making too direct of an accusation. Can someone share what mechanics the player might have used to cheat? Is the idea that a confederate might have been watching the match, getting a computer's help, and then some how signaling to him what move to make? Where was the game played such that this would have been possible?