Yeah, you really could have. It also grinds me when people will say "it's O(n), not O(n^(3/2))", because the former is a subset of later, not to mention talking

Yeah, you really could have. It also grinds me when people will say "it's O(n), not O(n^(3/2))", because the former is a subset of later, not to mention talking about worst case/average case/best case. Big O notation has nothing to do with probabilities, literally nothing.