Yes, I agree that it was his elevation that was the most problematic, and that you had to include a critique of Buffy in there, because, while her reasoning is understandable--she has a loyalty to those she feels will support her, and little thought to anything outside of that--it makes her a character who is as unconscious of her White American privilege as many of her real-life counterparts.
Not that I want to simplify Spike and Buffy's character arcs to a racism-lens, but merely to point out that the show's treatment (or lack thereof) of racial issues is rooted in the characters as much as in the show writers.