IMHO you and the parent post are both right: this is all around bad behavior by all parties involved.
I was let go once. I've told the story, but I have never mentioned the name of the company and I won't tell you if asked. I also had a horrible experience with a co-founder in my first startup to the point that I consider the guy a con man, but likewise I will only tell the story with all names and identifying details omitted. Calling people out in a public forum -- even if you are in the right -- just makes you look like an asshole.
But this response is also a terrible response from a CEO. He descends rapidly into the same muck as the original "AMA" poster. I agree that he was presented with two sucky options, but he should have taken the high road with his response and simply said something like "all I can say is that this individual was terminated for different reasons than the ones he states." In public at least, leave it at that.
Reddit in general is an increasingly toxic community. There was a great writeup a while back theorizing about various reasons that social networks select for snark, cynicism, and obnoxiousness over deeper and more thought-out content. If someone recalled it I'd love a link.