Exactly. On a purely technical level, it's just Gaiman trying to avoid the cliche of "Shadow examined his features in the mirror, his olive-dark skin and and sunken eyes blah blah blah". There's only so many ways to tell people what your character looks like. You can tell them directly, have the character see themselves, or see how other characters see the character. This is what Gaiman chose. Not only it is a deliberate choice, it's also a scene that performs multiple functions... which really, all scenes should do if you do them properly.

So saying that it's not about race? Yeeeeahhh, no. It is. It's not only about race, but it's silly to behave like Gaiman meant it to be about xyz and just happened to have race as the topic.