I don’t know what the implications of buying what he was selling are, but it’s possible that it functionally allowed players to cheat in multiplayer, which kind of ruins the experience of other players.
If it only affects a single-player game, on the other hand, I don’t really see a problem being caused.
I’d also add that I kind of feel that at least for this particular form, even if it is multiplayer cheating, while it’s probably not practical to mitigate every form of cheating in a multiplayer game, it’s probably possible to design the game in such a way that it can’t be attacked in this particular way.