DDOS of a mailing service that lots of websites rely on because a completely unrelated company decided to fire someone is not an occasion for lol and schadenfreude as some posters here would have it. As a method of justice it has more in common with a lynch mob than a court of law - this isn't going to get the guy's job back, and it certainly isn't going to teach anyone a lesson, apart from that the internet is fickle, and monumentally stupid. But I very much doubt the people behind this attack are interested in justice or truly care about the man who lost his job, they're just doing it for the lolz and are punishing the internet at large over a silly little dispute at a tech conference.
Congratulations to the mob, I guess; it has shown its power, if not any sense of discrimination or proportionality.