His opinion has not swayed me at all. I was a supervisor at a local company for 16 years. I know what a disgruntled employee is capable of. In the long run, he is just hurting his own credibility, and his ability to find a suitable job in the future.
There are a lot of things that we can't tell a human resources person when they call for a reference, or to check on an applicant's statement. But we have ways of letting potential employers that they are getting ready to hire a trouble maker.
Think about it: Who would want to hire this person after seeing how he has bad mouthed his former employer for three years?
He is a sick individual who has no life and will do himself in when he has nothing else to obsess about. We will read about him in the paper. That will be his swan song.
If people can't do their on D.D., they deserve to lose their money. If they want to listen to a crackpot, the same is true.