Although I have read and enjoyed several Moorcock novels in years past, I did not see much of substance in Moorcock’s views as described by the New Yorker blog post (FWIW, The Anti-Tolkien is a blog post; it is not in the latest print issue). In particular, the passage you quoted sounds like empty rhetoric from an aging pseudo-intellectual Marxist. Specifically, it raises several questions:

1. What makes Moorcock think that members of the middle class are apt to be morally bankrupt?
2. Are members of the middle class more apt than members of the upper and lower class to be morally bankrupt? If so, what evidence is there for this? If not, wouldn’t it be more descriptive to refer to “morally bankrupt society”?
3. Even if you accept that the middle class is morally bankrupt (which I do not), how is Tolkien’s “vast catalogue of names, places, magic rings, and dwarven kings” a “pernicious confirmation of the values” of that middle class? I don’t see any connection between a vast catalog of names, places, etc., and middle-class values (whatever those might be).