You’re right that I should explained that better. As it is: yes, you’ll detect an intersection whether the ray is normalized or not, but the distance to that intersection will differ depending on whether or not the ray is normalized. For this example, the distance doesn’t matter, just the fact of an intersection is sufficient.
So, yeah, maybe I could have left that off here. But the thinking was that for the next chapter, it would carry over. (See step #3 of “Putting It Together” in Chapter 6.)