I modded your comment up because it makes some important counterpoints to our usual knee-jerk "hackers good, businesspeople bad" mentality.
But let me join the chorus of people saying that we don't know enough to call him "the bad guy", even if only because he may not understand why shares usually vest in the first place (if you're a first-time founder who came up with the idea, you might reasonably believe you have an iron claim to your % of the company, even if it rarely works out that way in the real world).
By saying that he's "the bad guy" I did sort of imply that there is malicious intent on his side even though that may indeed not be the case. Perhaps he did not deliberately name the company he worked for in the OP to gain extra leverage, and perhaps he did not deliberately play the victim card and perhaps he really feels he deserves to get $12.8 million for his contributions. Perhaps.
And for what it's worth, I think he should get some compensation for his contributions and that the counteroffer of $0 is unreasonable as well, for the reasons given by other people.
But let me join the chorus of people saying that we don't know enough to call him "the bad guy", even if only because he may not understand why shares usually vest in the first place (if you're a first-time founder who came up with the idea, you might reasonably believe you have an iron claim to your % of the company, even if it rarely works out that way in the real world).