На воввики не сказано, что маунт должен бегать. Перейдя по ссылки на вовхэд, там написано:
Mount is now usable as a ground mount as of 4.2. Thank you for finally listening Blizzard!
И еще: http://us.battle.net/wow/en/forum/topic/1670090077
Цитата Сообщение от Restriction
12/26/2010
I just got a Blazing Hippogryph today, and once I mounted up on it and tried to use it in Tol Barad, I realized it was only a flying mount!

I am requesting it to be made usable on the ground as well as air similar to Invincible, Spectral Steed, Touring Rocket, or Headless Horseman's Reins!

This would make this mount so unique! Either way, thanks for making such a awesome mount!
от сюда видно, что до 4.2, маунт был, только летающим.
Бага нет закрыто.