My first day back at work this week , Rex took me downstairs and told me that he 'd heard that I was interested in Justin 's position . Justin runs the bulk department , placing orders and stocking stuff . He 's leaving for a week to move his family to texas . He 'll be back for a month , and then leaving for good .

Question: Why is Rex potentially interested in filling Justin 's position with the speaker after he leaves ?
Although he likes Justin , it is important to always have a backup plan and keep things running