Looking at that panel, it looks to me more like he comes from some point BEYOND the 24th century - he's zipping out from the metaphorical black clouds surrounding the area behind it. Anyway, that's a notoriously inaccurate means of representation - most comics/cartoons/whatever don't actually show the date that the time traveler is leaving as the dates flash buy - it's usually past decades that one sees, not present ones. And it's possible that, as you say, the whole thing was staged so that Super-American WOULD do exactly what their history says he did - but WHAT does their history say? Does it say more or less what ours would, or does it describe a world where Super-American runs rampant, thereby ultimately causing their society's formation hundreds of years later?