MC Carthy, when creating Lisp, decided on an abstract syntax that is fine and dandy for people doing program rewriting but never provided a human palatable concrete syntax.

McCarthy defined both S-expressions for symbolic manipulation and M-expressions for publication.

Note also that the distinction between concrete and abstract syntax parallels the distinction made by Chomsky between surface and deep structures.

I don't see that it does.

But some will claim that Chomsky is a fraud in linguistic.

Anyone making such a claim is a fraud.

This has nothing to do with his political opinions :)

For the most part, Chomsky quotes from public documents and draws obvious inferences. Quite in contrast to McCarthy, who is a standard-issue jingoist who indeed has nothing but uninformed opinion when it comes to politics.