Dont believe everything you read.
And you base that on what?
Obsidian clearly put a lot of effort into the storyline of New Vegas and It's multiple endings. For them to bow to the handful of whining and make a post-ending DLC would would display a complete lack of pride in their own work as any post-ending DLC would be unable to reflect any of the ingame decisions in a satisfactory manner.
There are four main endings, with four different outcomes, plus numerous other gameplay choices that effect the wasteland. No way they could accurately reflect all that into a little DLC.