Yeah it's nonsense. They try to make it a case of Grand Nagus Zek wanting to know what was going on on the front line. Which was trash.
Like a) the Grand Nagus would be interested in war machinations of the Federation - and not high level strategic stuff, actual on the ground tactics. and b) he'd send a fucking bar man.
The contrivance to get Quark into the Gamma Quadrant - that he was there to look after Zek's businesses interests, keep things sweet with the Karemma made more sense back in an earlier season.
In terms of why the writers did it, they said they wanted some one who wasn't Starfleet to provide an outside voice/viewpoint.