"Post-utopian" is a real term, and even in the absence of examples of its use, it is straightforward to deduce its (likely) meaning, since "post-" means "subsequent to, in reaction to" and "utopian" means "believing in or aiming at the perfecting of polity or social conditions". So post-utopian texts are those which react against utopianism, express skepticism at the perfectibility of society, and so on. This doesn't seem like a particularly difficult idea and it is not difficult to identify particular texts as post-utopian (for example, Koestler's Darkness at Noon, Huxley's Brave New World, or Nabokov's Bend Sinister).

So I think you need to pick a better example: "post-utopian" doesn't cut it. The fact that you have chosen a weak example increases my skepticism as to the merits of your general argument. If meaningless terms are rife in the field of English literature, as you seem to be suggesting, then it should be easy for you to pick a real one.

(I made a similar point in response to your original post on this subject.)