I stand by both comments.
The statement you refer to found here [link] is in regards to copying text (copyrighted or not) into biographies - I emphatically support the position that OUR content should be created by the members of OUR community.
This question however is about posting images (including pdf) of a copyrighted work to a profile. If a work is under copyright it is unlikely to be available to researchers on the numerous free sites out there (archive.org, hathitrust,org, google books, etc.).
In the (rare) event a copyright holder (who has been notified of Wikitree's terms, particularly on "Ownership and Use of Content") is willing to give permission to make their work, or excerpts of it, available on Wikitree - I would definitely post it to a profile so that it is available to researchers. As an image (rather than as editable wikitext) the integrity of the copyrighted work is maintained, but the content that appears in the biography is still created by members of our community.
There is no value in uploading books that are uncopyrighted or out-of-copyright to profiles because those can already be made available to researchers on sites like the ones already mentioned (archive.org et al.). That is their purpose.