You know, you'd probably get a kick out of Utah Philips. If you haven't already, check out the spoken-word album he did with Ani DiFranco, The Past Didn't Go Anywhere. It's good stuff, and he has a bit where he discusses the "arsenal of privilege" he, as a white man, was born with.
I'm actually a little irritated that you think that Derailing for Dummies link applies here, though. I'm not using any one of those arguments, unless you're actually from Brunei and that's why you're pissed.
I'm saying that you see an egregious racial stereotype, and I'm seeing a fat douchebag in a robe who looks like Ron Jeremy, in a book where everyone is ugly and has bad teeth. The sultan's nephew's douchebaggery has nothing to do with being related to a sultan, a Muslim (see his reaction to the traditional greeting, when he should've hit the dude right back with wa alaikum assalam?), or from Brunei; it has to do with being a douchebag.
He is a lecherous douchebag with a big mustache and a white robe, which means he is unfortunately stereotypical about it, but he remains a simple douchebag, emblematic of nothing. He is not carrying a scimitar, strapped down with explosives, accompanied by twelve women in diaphanous harem pants, or despoiling Christendom; he is Young Irresponsible Yasir Arafat, and a story that features a young and irresponsible member of a culture is not racist simply for existing.
Accuse Parker of getting facts about Brunei wrong, and I'm down with that. Accuse Hotz of drawing the sultan's nephew to look like that guy from "Ali Baba Bunny," and sure, I can see that.
Latching onto this as an example of any kind of racism, though, looks like you're looking for something to get pissed off and righteous about. Honestly, the more I look at it, I'm seeing an artist who makes everyone look like Gollum, being asked to draw a dude in an Arabic robe, and wackiness has ensued.