Well, making a map and enabling the same cheats bilzzard has on their one player games would be the way to do it...its just like when you play a tower defense map and you can sell towers by entering "-sell" while selected on the tower you want to sell.
He just has to create the "triggers" to make it do the same thing blizzard cheats do when he makes the map.
So, if you dont want him to cheat, just play blizzard maps..