I don't see any evidence either way for whether or not his "keepgrabbing" python soup only grabbed public domain articles. At the very least, I imagine it touched the landing pages for each article to get the pdf link, where it would also have an opportunity to look at the copyright status. Is the copyright status even on the JSTOR page for each article anyway? Or is it only in the PDF?

Let's see..

http://www.jstor.org/discover/10.2307/1831029

The "rights and permissions" link goes out to:

https://s100.copyright.com/AppDispatchServlet?author=Fischer...

... ok copyright.com is not encouraging at all, that scam is everywhere. Let's try something older.

http://www.jstor.org/discover/10.2307/30096268

The "rights and permissions" link goes out to:

https://www.copyright.com/openurl.do?sid=pd_ITHAKA&servi...

which leads to:

http://www.copyright.com/search.do?operation=detail&item...

.. where they seem to be selling the rights??