The point is that she's part of a demographic in which racism is bitterly endemic, shown clearly in TME.
I haven't had the impression Vivienne is "part of" the Orlesian nobility. I read "outsider" into her position at court. I see her snobbish, well dressed, Iron Lady persona as her personality on steroids played to impress nobles and gain social currency to spend later telling them what their views on mages and other things should be. I don't doubt that she's conservative on some or many issues, I don't doubt that she can be brutally cutthroat when it comes to it for a cause she supports, and I don't doubt that she's materialistic on some level, but a through and through rotten to the core Orlesian noble, I don't think so.