books.google.com and archive.org have a lot of content. Depending on his interests, its possible if not probable that he has not pirated anything because most of his collection is too old to be under copyright.

Maybe his ebook collection consists primarily of product user manuals (pdfs straight from manufacturer websites), or pre1926 trade manuals (hey, I know a guy who collects antique light fixtures...), or he dabs in genealogy and has a few GB of pre1926 genealogies (not all surnames have had their genealogies re-done in print since then).

Its a stretch, sure. But its possible.