In at-will employment states (like Kansas and Missouri, for example) an employer has the right to terminate an employee for any reason or a bad reason, so long as the basis is not illegal. There are public policy exceptions (such as serving on a jury, voting, or testifying in a hearing) and exceptions where the decision to terminate is based on a violation of civil rights laws. Beyond that, however, there is a fairly free hand by employers to hire and fire. Firing someone for their social media posts is permissible except if the post address wages, hours and working conditions. The National Labor Relations Board has held that it is a violation of the law to fire an employee for a social media post about wages, hours and working conditions. So be careful in how you evaluate the post if you feel you must terminate an employee about a social media post.