User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-10487081-20130424022526/@comment-3146930-20130424104127

Not to mention that Zeus didn't seem to mind Percy flying in the Argo II even though he told Percy never to enter his domain again. Considering the Argo II is a ship, something in Poseidon's domain, Zeus doesn't really have any say in where the ship flies.