As I recall that statement was quite some time before the launch of the game, plans could change. Not that I disagree though, I think the DLC will be intended to be post-game, but not for the reason you mentioned. Solas is clearly a companion in the picture, and the simplest explanation is that you can choose whether to do the DLC before or after completing the main campaign. That being said I think they'll want to keep the story moving forward, so the intended timeline of the DLC will be post-campaign.
Have to say, I'm feeling rather positive about this one, the pictures and the premise of it is giving me Legacy vibes 
Legacy was a great DLC (and turned out to have especially worth playing, given Inquisition!), but what made it for me was the family connection to Hawke. I'd love something to give Quizzy a bit of background because them being so unknown is kind of preventing me getting as attached as I am to the other two. I'm not optimistic, though - they'd basically need what, five different origin stories? And how could you have them all be tied to the main story of the DLC. Ah well.
Lawd, it's hinted Maryden is trying to woo Sera with her songs. If she's doing the same with Leliana... *Warden sharpens knives*
Ha! Leliana would be having none of that. I wish the Inquisitor had flirt options with her, so as to be gloriously shot down.