I'm not sure why the negative reaction to this post. I found it completely plausible and have no reason to doubt the author. It sucks that there are crappy people like this but unfortunately that's the real world. People will exploit you if you allow them to.

That said, threatening to sell exploits on the black market is a terrible way to fight back. Everything up to that point suggested the author had a case he could argue in court. If he does indeed proceed down that path he would likely find himself on the wrong side of the law.