Wow, you've done your number crunching there fromdgrndup. Although fuel consumption is a large chunk of how an airline chooses what engines they use, there are other factors as well, such as maintenance cost and time between such maintenance. Remember an airplane in a hangar is not making money. And an airlines number one goal is to make money, but if you go for a job interview, please say "safety" instead.
For e.g. when entering data into the FMS, we always use a slightly higher cost index as although we could always just enter zero and get there using the least fuel, BUT, although it burns more fuel, we could squeeze a couple more revenue flights in before the scheduled maintenance or down time.
Say that in your airline interview, I promise you the interviewers will be all hot and heavy for you...