I'm not an English major, but I'm with barcodegurl on this one. A similie compares something to something else, a metaphor describes something as if it *were* something else. A metaphor would be "his thoughts were a load of underpants in a dryer without Cling Free..."
Also, I read it and thought "hey, that reminds me of that page of bad analogies!" So I went and found the page and was gonna refer you to it, when I realized that that is exactly where this quote came from. So yeah, I'm guessin' you already know about it :)