I don't agree with all of this post, but it is the most well-reasoned statement I've seen on this incident to date, and I appreciated reading it--and I agree completely with your conclusion that "the difficulty in getting non-straight, non-white, non-"mainstream" characters through the filter of authors' brains, agents' judgement calls, editors' purchasing power, bookstores' support, and readers' inclinations, all the way to the public eye" is the part that really matters.