Thank you for your comments!
We started out with the idea of a module based on the story of Layla and Majnun, and that led us to adding stuff from other Jinni mythology. The brass is mainly a reference to the 1001 Nights story of the City of Brass (considered to be one of the oldest known sci fi stories) as well as to the idea of a brass Jinni lamp.
As for decoupling the ship, the idea is that if Qays does not want the PCs escaping with the Bottle, so if Solomon is neutralized then Qays won't let them escape. In testing we determined that if the PCs defeat Solomon, the adventure needed something to prevent an easy getaway.