> In art history, literature and cultural studies, Orientalism is the imitation or depiction of aspects in the Eastern world.

GGP is not using a slur, they're suggesting that this is an inappropriate use of Japanese culture as an aesthetic by a Western writer. Reducing a culture to an aesthetic is harmful because it essentializes and stereotypes a culture and those in it.

(I don't know if I agree about this particular example or not, I'm still pondering; only explaining.)