Fired because of Facebook?

After reading this article, I believe that Apple had every right to fire the employee.  "According to the initial report, Apple “made it absolutely plain throughout the induction process that commentary on Apple products, or critical remarks about the brand, were strictly prohibited”",  this line, being pulled directly from the article, proves that the employee knew the companies policies on social networking, and yet still decided to make the negative comment that they did.  As the employee, yes I would be mad about the decision, because to many it can still be seen as an invasion of privacy.  Social networking is about being social  and a job deals with your career, the two should not coincide, however, since more businesses now use social networking to reach new customers, they do coincide and you have to watch what is said.  As an employer, I would fire the employee, because we may lose business due to them and their negativity.  An employer could have easily hired someone more positive and willing to bring in new customers and talk highly of the business.