Correct, I have a Shaman that I've had camping Houlon in the Timeless Isle since patch Broken Shore was released, and haven't touched Argus at all on her, I don't think I've even done more than the introductory Broken Shore quests, her ilvl is in the 840's if that tells you anything, just for completion I went down and knocked out the silithis quests on Saturday morning before putting her back in the Timeless Isle where she'll sit until I get that damned mount. 76 kills since I started counting, and probably a good 30-40 kills uncounted, and I still don't have it.
Speaking of the Timeless Isles, it irks me that I can't go to the north of the Island because I didn't play in MoP. I get that there are limited time events, which I'm all for. What I dislike however is that there is a section of the current game that I can't play, because I didn't do a Legendary questline that is no longer available. I don't even know why we're being locked out, it's not like the World Boss up there drops anything unique.