Don,
It's only an admin configurable setting as to whether it would get posted. Our logic for that is simply, it's your site, and so generally, you'll know the types of topics your users will be posting publicly, and if they would want those pushed back to Facebook.
We do respect the Privacy settings of JomSocial 2.2+, so only if a user marks a message/status update a public will it get posted to Facebook. In this case, again, our logic is simply "it's public anyways, so Google, or anyone else could easily find that post". So, it's up to you as admin to decide if these public posts get automatically pushed back to Facebook, and that really depends on your site's nature.
Your user's have an additional mechanism to stop posts going back by not granting the "Status Update Permission" for your site to post to their wall. If it's set as required though, it means that they won't be able to login via Facebook, but again, that's their choice.
Hope that helps explain everything,
Alex