Don't play minecraft personally, but i just want to clarify a couple of points to define "cheating." Cheating has to be done to someone, by someone. In single player games, if he uses cheats, he loses out. In multi, other players can lose out too.
Take a standard basic shooter. If you hack into the code and make it so your gun fires 100 rockets a second the game mechanics are broken, by the player, to gain an unfair edge upon other people.
Where the cheating is actually done is actually by himself, on himself. He kills all the challenge that the game mechanics imposed on him, and all he is doing is making the game mundane for himself.
Now, consider this. The developers have put this gun in as a perfectly legit pickup (COD heli anyone?). In this case, the game mechanics are already broken.. and it's the developers that have left it in and essentially, they are the ones cheating the gameplay out of it's players. This is mostly unintentional, and can be discounted as being malicious, but it still can be cheating the player out of the challenge.
So in short, if the game mechanics are allowing ways to cheat, then you're not to blame for using them to your advantage, they just shouldn't be in the game in the first place. You as a person can choose against using them to increase your challenge, but just keep in mind that people who abuse broken parts in the game, are just playing the game too.