Are you sure you aren't just pattern matching to similarity to known types of blackmail? Do you think it would be useful for an AI to classify it the same way (which was the starting point of this thread)?

Your link doesn't go into much detail, but it seems like he was convicted because he was lying and making up the negative consequences he threatened her with, and like he was going out of his way to make the consequences of selling to someone else as bad as possible rather than maximizing revenue (or at least making her believe so). That would qualify this case as blackmail under the definition above, unlike either of our hypothetical examples.