User blog comment:Suparockr/List of Plotholes throughout the series/@comment-3228423-20120717025201/@comment-4950455-20120717025750

The answer to this has been stated repeatedly - in the original planned ending, the Reapers' "purpose" was to stop the spread of dark energy rather then to stop synthetic-organic war. When that was changed to what we got, Haestrom was left dangling.