Well, it's not a matter of free speech. If she was arrested and thrown in jail, it would be. I don't agree with the reasoning she was fired for, but it is true that when you work for a company, you are representative of that company, and if they view you in bad light for, in this case, social media comments that they feel are detrimental to their image, they can get rid of you. There's not a whole lot of "freedom" in the workplace. It's their way or the highway. If it's company policy for you to wear a uniform, you wear it. If it's company policy to have short hair, you cut your hair short. If you want to be free spirit and take a stand against their policies, you're fired, but you're free to work somewhere else.