From the comments on Wowhead:

"There is a nearby statue of a dragon (presumably a young Neltharion?) at 43.57, 23.02. Stand in front of this statue and /kneel. The statue which is normally inanimate will have its eyes light up and breathe fire. At this point, the Fealty's Reward chest becomes lootable!"

I just did that and indeed works. The chest gave me Crest Fragments, Flightstones, Dragon Isles Supplies..... and a trinket: Drakeforged Magma Charm.

As additional info:

• you have to /kneel while not riding a mount. I did that first and saw the action text but there was no reaction from the statue.
• on the wowhead comments they say that if you take too long to go back to the chest it can't be clicked on. Make sure to go back quickly.

Already changed in commit e626556.
This will be included in the next release.