It's not career suicide. People should talk about shitty places to work more often, and there's no way Zynga can keep another company from hiring the guy. The only time you see "you'll never work in this town again!" work is when all the companies are colluding to control the labor market. In programming that hasn't happened yet, so he can say pretty much whatever he wants and still get a job.
In fact, it was easier for me to get a job after I demolished Ruby on Rails for being the piece of shit that it is. People like honesty.
In a perfect world, people would be able to expose employers who are doing wrong with impunity. In the real world, it's difficult to do so without repercussions. How do you think companies like Zynga can still recruit developers?