"Seems riskier than taking the transport. A lot easier to take out one broom than a whole ship. And easier to cart away wounded and casualties than hauling bodies along on a broom built for one."
"Plus, you know, supplies are important." he says as if this last thought doesn't really need to be said, but he'll say it anyway.
Also airships don't rely on waterways so I'm assuming Dakaal would recognize that and come up with a similar objection for a flying ship.