It makes you wonder if Sauron (or his agents) were searching out the last brood of FBs or if they just found them by accident. I should imagine Sauron was delighted as they must have been fairly pliable in terms of training, to get them ready so quickly for flight. And you simply cannot imagine any Dragon allowing you to ride on his back. So they were probably the only creatures capable of flight available for his use.
I still feel sorry for creatures like this, the last of their kind, wiped out in warfare, like the Mumakil.
Though those 'fell meats' still intrigue me, as there must have been a Hilary Briss operating in Middle-earth
