^To be fair though, that last point is more of a plot contrivance than anything else.
I can see ways that DS9 could perhaps have been integrated into the show...maybe one of the Defiant-class ships actually is the Defiant, and Prometheus gets boarded by some DS9 folks? But any kind of substantial interaction would to my mind also generally involve a substantial rewriting of the episode.
So, barring the possibilities I mention above, I don't think this was intended to involve any DS9 folks. It might have been nice, or might have felt token.