I'm opening this meta to provide an place for discussion about the general issue of copyright and Genealogy.SE and/or discussion about this relative to the referenced question.
As part of the question, "Locating additional details on 'Thomas Tunin' - b.1836, d.1912," our community member provided a meaningful set of contextual information. When asked, links to sources were added.
I viewed each of the sources to learn a little more detail, including that I followed whatever references there were to discover what seemed basic ownership, dates, etc.
- The family tree information. I'm not an attorney, but I found this information to consist of "facts" (names, dates, places). Generally US copyright does not protect "facts."
- Family narrative. This was developed from a message posted 1998 to a RootsWeb hosted mailing list (OKDEWEY-L), and the author of the post cites, "'Spanning the River,' Dewey County FFamily Histories Vol. 1." I tried to chase down that reference; discovered notice on the page "Dewey County Oklahoma Publications," reporting a publication date of 1976. I don't have a copy of the 1976 work, so I can't know if the RootsWeb post (1998) is a summary or extensive quote from the 1976 work. In either case, though, what is posted to StackExchange seemed it was an extensive quote from something that would be subject to copyright.
- Tombstone photograph. The source for the photograph appears on a USGenWeb page (OKGENWEB - Dewey). I didn't find any creative commons license on that page; it carries a reference to Susan Bradford, however, and the page is reported last edited in 2008. Generally, modern photographs are creative works (thus subject to US copyright; see Copyright. "Can I use Someone Else's Work..."
At least it wasn't clear to me that permission had been granted regarding the family tradition and/or photograph and I didn't take the fair use issues further than my own rules of thumb.
I didn't flag the question, but in my answer, I commented and asked our community member/poster to revisit the question.