It's definitely just the last Dragon Isles creature we will ever get. I kind of agree it may have been cut content as it would make sense to design a regular Draconic Owl in some patch, and then have Anurelos reuse its rig for 10.2, but between the color, necklace and the design of its saddle its 100% tied to the Blue Dragonflight.
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There's that too. It was obvious that the Jailer was a royal figure in his old design. However, the chest hole and Arbiter's orb made it equally obvious on the new design, so I'm unsure just how "secret" it was meant to be.
If anything, if they dialed back the royalty jewelry on the old Jailer design, but let him keep the beard (covering his chest hole), it would be a really clever way to hide it.