I'm sure it's a fake.
And yes, you can be fired for anything at any time. In certain professions, anyway. Doctors, lawyers, and teachers, for example, have been organized into professional organizations for over 100 years, and it's actually pretty hard to fire them. Union workers can't be fired on a whim either. Government employees can be fired, but it's really hard, because the govt has a responsibility to keep people working. But low-level people working for a corporation? Yeah, Ballmer could theoretically fire one for not being excited about the name of the new search engine.