Many people have gotten fired by saying something politically incorrect on Twitter or Facebook. When free speech is called into question, the standard response

Many people have gotten fired by saying something politically incorrect on Twitter or Facebook. When free speech is called into question, the standard response is that it's not protected because a company is not the government and can do as they please. This is the other side of it. Based on this same thinking, a company can also fire you if they don't think your marijuana usage looks good for their image.