Given that mafia can still mean a criminal organization when not capitalized (since the third definition is often not capitalized but not always), it is up to Mr. Bigger to explain what he meant.
Given that he was describing a seeming collusion with financial ramifications it is pretty obvious he was sending the message that something underhanded and probably illegal is happening and that more than the idea of a clique of mean girls at school seems to be what he was evoking though I am sure he can hide behind your explanation.
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