Best I can suggest is set your login redirect to send them to profile edit. Professional subscriber plugin CB Progress Field can auto redirect to profile edit if a required field is incomplete, but it won't force them to stay there. For that you'd need a custom Joomla system plugin that checks a users profile data on every page load. If you know what value you want the field to have and they are all the same you could run a database query in phpmyadmin to update every row in _comprofiler.