Druid flight masters at Moonglade doesn't have an option to provide a flight for druid players. It seems to be true for both fractions (Horde and Alliance). Attached screenshots as a proof.
Can't find info in details about prerequisites for using them (except for being a druid ofc).
But they at least should be usable during first druid class quest chain to get the Bear form. No special actions connected with flightmasters. It is stated in guides (in context) that druids just can flight away to their capitals or use heartstone for timesaving.
All they have is just a common NPC text.