You don't need CBSubs for that. You need CB Content Bot, which allows substitutions in all content prepare usages (e.g. Joomla articles). Once installed, published, and public you can use an IF substitution to limit a specific part of your article to a view access level, usergroup, or even a field. Example as follows.
Code:
THIS IS VISIBLE TO EVERYONE
[cb:if user="#me" user_id>"0"]THIS IS VISIBLE TO LOGGED IN USERS[/cb:if]
See the below tutorial for further substitution usage information.
www.joomlapolis.com/documentation/279-community-builder/tutorials/18353-using-substitutions-throughout-cb