I believe Fabi, but the question must be asked: how does he know (with certainty!) that the player was cheating. Did the player confess? Was he blatantly looking on his phone in front of him?
I am completely certain, because I saw the evidence myself.
But to anyone else? There's no hard evidence - just he-said-she-said. Maybe I was mistaken - or trying to get my rival into trouble.
Knowing how it would look, maybe I keep my mouth shut rather than throwing around wild, baseless allegations about cheating.
(down to #8 now, I suppose)
In this case, his off-the-board behavior, where he seems unable to explain some of the moves he made, is also suspicious. His skill set is such that there's no move he's not capable of playing, though he should at least be able to tell you what he was thinking when he played it.