I dunno, the way the graphic is phrased strongly suggests that Sisko's fate is still an "unexplainable" mystery. Speaking as a former history major, I don't recall any course syllabus ever describing a course about a known historical event in terms implying that it was an open question. An advertiser concocting a promo for some sensationalist cable-TV pseudohistory show would have no compunctions about writing such misleading copy, but you wouldn't find it in an academic setting. A course description would acknowledge what is known and say that its specifics and meaning would be examined, but it wouldn't ask elementary questions about whether it happened at all.