If the presentation didn't make it clear, I have to write it's time to ask the author to follow up with an addendum.
-> By the way, if you go back decades to the Mainframe Era, that was a secure computing system. You would use a terminal and not allowed to do anything that wasn't in the menus.
I have yet to find anyone but old school mainframers wanting to go back to those systems.
Guys what are the shortfalls and strengths in an article ''NETWORK SECURITY: AN APPROACH TOWARDS SECURE COMPUTING" Rahul Pareek from MCA Dept. Rajasthan College of Engineering for Women.