I’m not convinced by Michael Minnich‘s account, which makes a French Swiss linguist a Teuton. But it is certainly true that poststructuralism, as a European invention, was always going to draw more inspiration from what was happening in the generation of the European linguists who had trained the first poststructuralists, than in what was happening at the same time across the Atlantic in linguistics.
That aside, there is an internal reason why de Saussure was more useful to the post-structuralists than Chomsky. De Saussure’s structuralism emphasised both paradigmatic and syntagmatic relations of signs. The European structuralists generalised his semiotics, applying it outside of linguistics. And outside of language, the syntagmatic relation does not do as much work, and is not as complex, as the paradigmatic relation.
The point of Chomsky was to elevate syntax as the primary domain of linguistics. Outside of language, syntax just isn’t as important in sign systems. So what Chomsky was up to simply wasn’t as useful to those philosophers and semioticians.