I think there's a time and a place for public dissemination of emails like this. To take an example, TechCrunch does it all the time - sometimes I think it goes too far (every single internal email AOL sends out), sometimes I think it's appropriate (eg the "snark" email from Moviefone
http://techcrunch.com/2011/03/15/snarketing/).
In this case, where there is virtually zero chance of legal proceedings actually resulting, and the protagonist is simply venting / bullying / baiting the recipient, I think publishing an email publicly is a decisive statement that you think they're silly, ridiculous, and should go away (it's also a good read and nice publicity). From a legal perspective, you don't really lose much, if any, ground.
Also, for what it's worth, even if this guy is considering the "corporate veil" (that's a big if), and even if he has a shred of a cause of action (even bigger if) then knowing he's going after individuals is even less appealing that going after a nascent company (much harder to extract money and legal fees from a 22 year old student).