I haven't called Pioneer but I kept looking and I can't find any mention of an adaptor; all the reviews say no satellite radio. Obviously you could add a Sirius receiver and mount it on the dash but that does somewhat take away from the setup.
Oh well I was rather excited when I read the post but I really like my Sirius?XM on the road.
Good luck with the sale!
Disclaimer: I'm getting old and my opinions will reflect that fact!