Came here to say the same thing. Just use SciHub.

Looks like it's covertly suggested in #5

    5. Install Browser Extensions

    Browser extensions can help you check the web for free versions of academic articles. 
    The Unpaywallbrowser extension gathers content from more than 50,000 journals and open-access repositories worldwide. 
    The Open Access Button searches “millions of articles” from sources that include “all of the aggregated repositories 
    in the world, hybrid articles, open access journals, and those on authors’ personal pages,” according to its website.

    If the Open Access Button does not find free versions of the articles you’re looking for, it will contact the authors and
    ask them to share their work by putting it into an open access repository.

suggest it to the article author :)

I suspect the oversight is intentional. The other methods are uncontroversial. The mention of the OA button is a nod to it, without going into the arguments over Sci-Hub's legality.

How is it a nod to scihub?

There's a sci-hub now browser extension.

But that is not the two extensions being recommend. On the contrary the two extensions are ones that tries to respect copyright.