Reviewing through your description the following message template jiveURL/admin/message-templates.jsp?action=edit&template=userinterceptor.email is used for both scenarios you have outlined above.
I would think there should be a separate mail template for disable login vs disable post.
While this is not available in the current platform, if this is a feature you are interested in seeing added to a future release, I would recommend submitting an idea to the Ideas for Jive space where our Product team reviews through top rated ideas when considering feature enhancements.
Odd. The default message for the template specifically speaks to banning posts and doesn't mention ban login at all. So it seams that the ban login version is missing. I'll create an idea.