Well yes, that's what I said, although I guess I could have used 'n + x operations' to keep it consistent with the article and still in line with the formal definition.
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.