Found a Backupify blog on controlling employee access to social media odd. Preventing employees from discussing work on social media may help, but really you need to operate like the Manhattan Project. Sequester them in a town you build in the middle of nowhere, go through all of their correspondence paper or electronic, and control who they can physically see. People are going to talk about what they do.
Really, the issue is a business whose survival relies totally on secrets is one blabbermouth away from total destruction. The secrets are the problem not the employees. When owners and managers get to the point they cannot trust employees, the employees need to leave and take all their knowledge with them.