There is a portal from Dalaran to Org, I took that and flew myself to Silitius, I managed to complete the quest, but then it auto ported me back to Dalaran before I could hand it in, will try again and see if i can make it to hand in .
Update : went back to Maelstrom, found a portal beside Advisor Sevel who is up by scouting map, called some weird name, took it, and popped out in Silithus … right at quest hand in . go figure.