Fine reasoning going on here. I like it. Scott's point seems to be that if the site is a straight-up profit-maximizing business, it would not reject gay customers. Rejecting potential sales is a considered choice. Some other value is being served. So the question becomes this: Is there a category -- a legitimate specialization -- that sells social leads to white heterosexuals only?
Scott's take is that since white heterosexuals can find mates on most dating sites, a specialty site for them becomes, ipso facto, a racist political organization. If so, what would be its "mission"? What would be the "vision" of its creator? Solve for that and you might get a very interesting picture of the future.