Basically, manipulating the symbols won't necessarily have any long term influence on your own state. But the variables you've touched on the paper have changed. Demonstrably; because you've written something down.
If you then act on the result of those calculations, as of course many engineers before you have done, and many after you will do; then you have just executed a functional state change in physical reality, no matter what the ivory tower folks say.
(And that's what the paper is about: Functional states)