This is of course Correct (pun intended)... but IMO the underlying meaning of correctness was a correctness of the abstractions to the problem domain and that correctness ultimately boils down to the expressibility of the language that allows it to create the correct abstractions. This interpretation might have to do with my having known many fans of Lisp (of which I'm one) and that people who love Lisp (like the author of the paper) are usually big expressibility proponents.