The way I see it, Mok did absolutely nothing "wrong". He read no modules in advance and deduced a puzzle.
He uses the same kind of reasoning that a player uses in order to pick up on an adventure hook. The same kind of reasoning that ultimately allows for non-sandbox modules to run.
As a community, I think we often undervalue the positive aspects of metagaming. The term itself is anathema and emotionally charged.
But responsibly (read: without cheating) steering oneself in a way that makes the game more engaging is a good thing right?