I don't know if this is because I made a Dracthyr during the free weekend of play back in March or if you don't even need a Dracthyr at all.
I really liked Dragonriding for those couple days, so when I was flying in Uldum, I figured I would talk to the dragon and see what happens. Turns out it isn't expansion locked, which really surprised me. I only have 3 energy boost orbs so I am definitely limited with what medals I can get, but I was able to get gold normal and bronze advanced and reverse on the first attempts.
I assume I can't spend the tokens because the vendor is in Valdrakken, but I haven't tried getting to those islands.
For any achievement hunters, don't forget to talk to the little dragon.
I hope this is intended and Blizzard doesn't change this