There's a sense in which a lot of fuzzy claims are meaningless: for example, it would be hard for a computer to evaluate "Socrates is kind" even if the computer could easily evaluate more direct claims like "Socrates is taller than five feet". But "kind" isn't really meaningless; it would just be a lot of work to establish exactly what goes into saying "kind" and exactly where the cutoff point between "kind" and "not so kind" is.

I agree that literary critical terms are fuzzy in the same sense as "kind", but I don't think they're necessarily any more fuzzy. For example, replacing "post-utopian" with its likely inspiration "post-colonial", I don't know much about literature, but I feel pretty okay designating Salman Rushdie as "post-colonial" (since his books very often take place against the backdrop of the issues surrounding British decolonization of India) and J. K. Rowling as "not post-colonial" (since her books don't deal with issues surrounding decolonization at all.)

Likewise, even though "post-utopian" was chosen specifically to be meaningless, I can say with confidence that Sir Thomas More's Utopia was not post-utopian, and I bet most other people will agree with me.

The Sokal Hoax to me was less about totally disproving all literary critical terms, and more about showing that it's really easy to get a paper published that no one understands. People elsewhere in the thread have already given examples of Sokalesque papers in physics, computer science, etc that got published, even though those fields seem pretty meaningful.

Literary criticism does have a bad habit of making strange assertions, but I don't think they hinge on meaningless terms. A good example would be deconstruction of various works to point out the racist or sexist elements within. For example, "It sure is suspicious that Moby Dick is about a white whale, as if Melville believed that only white animals could possibly be individuals with stories of their own."

The claim that Melville was racist when writing Moby Dick seems potentially meaningful - for example, we could go back in time, put him under truth serum, and ask him whether that was intentional. Even if it was wholly unconscious, it still implies that (for example) if we simulate a society without racism, it will be less likely to produce books like Moby Dick, or that if we pick apart Melville's brain we can draw some causal connection between the racism to which he was exposed and the choice to have Moby Dick be white.

However, if I understand correctly literary critics believe these assertions do not hinge on authorial intent; that is, Melville might not have been trying to make Moby Dick a commentary on race relations, but that doesn't mean a paper claiming that Moby Dick is a commentary on race relations should be taken less seriously.

Even this might not be totally meaningless. If an infinite monkey at an infinite typewriter happened to produce Animal Farm, it would still be the case that, by coincidence, it was a great metaphor for Communism. A literary critic (or primatologist) who wrote a paper saying "Hey, Animal Farm can increase our understanding and appreciation of the perils of Communism" wouldn't really be talking nonsense. In fact, I'd go so far as to say that they're (kind of) objectively correct, whereas even someone making the relatively stupid claim about Moby Dick above might still be right that the book can help us think about our assumptions about white people.

If I had to criticize literary criticism, I would have a few vague objections. First, that they inflate terms - instead of saying "Moby Dick vaguely reminds me of racism", they say "Moby Dick is about racism." Second, that even if their terms are not meaningless, their disputes very often are: if one critic says "Moby Dick is about racism" and another critic says "No it isn't", then if what the first one means is "Mobdy Dick vaguely reminds me of racism", then arguing this is a waste of time. My third and most obvious complaint is opportunity costs: to me at least the whole field of talking about how certain things vaguely remind you of other things seems like a waste of resources that could be turned into perfectly good paper clips.

But these seem like very different criticisms than arguing that their terms are literally meaningless. I agree that to students they may be meaningless and they might compensate by guessing the teacher's password, but this happens in every field.