I expect that he didn't substantiate his claim for the same reason the original poster didn't substantiate his claim that learning C is a good use of time - people around here who have done both likely appreciate the value of the task.
Meta-point: I think a lot of people around here who argue "school is worthless, why am I doing this useless task" will point to this sort of exercise without asking or understanding why it's done. I certainly felt the same way when I was memorizing Shakespeare. While it's important to think for yourself, it's also important to take the advice of those who have more experience than you do, and when I see these threads I think many of the commentators haven't learned both lessons.
I think you would understand my position better if I clarified that it was memorization of the lines I was being graded on not the understanding of what the lines meant. That is the issue I took with the assignment.
Learning C is an objectively better use of ones time than memorizing X because learning C requires that you think whereas memorizing X requires that you simply spend time committing the order of symbols to memory.