In so doing you saved the company the cost of finding, hiring and bringing your replacement up to speed. It's a bullshit argument because the speaker doesn't care if you believe them.
I'm certain there's a bad date analogy somewhere in there too! :D
I would add that if you are in the knowledge industry, the benefits of keeping knowledge from walking out the door can be significant. The benefits of good will from employees and former employees can be especially beneficial when it comes to acquiring staff.
Leadership means going to bat for one's subordinates. It is a quality which distinguishes good management from mediocre.