Well... no matter which forum section you visit, someone is always trying to prove something. Replay the game and that's it.
As I understand it, this is a screenshot from day 126, and if he picked up the lookout tower on day 124, let's say, then I can certainly assume that the guard was broken by you on, say, day 121 and you are heading back. This is a beginners' tournament, so mistakes can happen.

P.S. Besides, if he could defeat the genies without any issues (having oil available), then it becomes even more obvious that this was a simple mistake, not a deliberate violation of the rules.