To ensure your Facebook posts are public when posting through the Social Media tool, you may need to change the application settings in Facebook's Applications.
First, log into the profile you use to manage your business accounts. Then navigate to this page: http://www.facebook.com/settings/?tab=applications.
One there, scroll through the list of applications to find the "Social Dashboard" application and click the little edit pencil:
Here you can adjust the settings for how your posts are published through the tool. Choose "Public" if you'd like your posts to be public on Facebook.